Method for isolating hepatitis c virus peptides

ABSTRACT

Described is a method for isolating Hepatitis C Virus peptides (HPs) which have a binding capacity to a MHC/HLA molecule or a complex comprising said HCV-peptide and said MHC/HLA molecule characterized by the following steps: —providing a pool of HCV-peptide, said pool containing HCV-peptides which bind to said MHC/HLA molecule and HCV-peptides which do not bind to said MHC/HLA molecule, —contacting said MHC/HLA molecule with said pool of HCV-peptides whereby a HCV-peptide which has a binding capacity to said MHC/HLA molecule binds to said MHC/HLA molecule and a complex comprising said HCV-peptide and said MHC/HLA molecule is formed, —detecting and optionally separating said complex from the HCV-peptide which do not bind to said MHC/HLA molecule and optionally isolating and characterising the HCV-peptide from said complex.

The Sequence Listing is submitted on one compact disc (Copy 1), together with a duplicate thereof (Copy 2), each created on Aug. 18, 2005, and each containing one 344 kb file entitled “SONN059SEQ.txt.” The material contained on the compact disc is specifically incorporated herein by reference.

The present invention relates to a method for isolating HCV-peptides, especially for isolating HCV T cell epitopes which have a binding capacity to a MHC/HLA molecule.

The immune system is a complex network of inter-related cell types and molecules, which has evolved in order to protect multicellular organisms from infectious microorganisms. It can be divided into the evolutionary older innate (or natural) immunity and adaptive (or acquired) immunity. The innate immune system recognizes patterns, which are usually common and essential for pathogens. For this limited number of molecular structures germ-line encoded receptors have evolved. By contrast, cells of the adaptive immune system—B and T lymphocytes—can recognize a huge variety of antigenic structures. The receptors, termed according to the cell types expressing them, B cell receptor (BCR, its soluble versions are called antibodies) and T cell receptor (TCR, only cell-surface associated forms) are generated by somatic recombination and show a clonal distribution. Thus, initially there is only small number of cells with a certain specificity. Upon antigen encounter these cells start to divide (clonal expansion) to generate an effector population able to cope with the antigen. After elimination of antigen a specialized sub-population of cells specifically recognizing this antigen remains as immunological memory. Taken together the adaptive immune system is slow (compared to innate immunity), however specific and it improves upon repeated exposure to a given pathogen/antigen.

T cells have a central role in adaptive immunity. Their receptors (TCRs) recognize “major histocompatibility complex” (MHC or HLA):peptide complexes on the surface of cells. These peptides are called T cell epitopes and represent degradation products of antigens. There are two major classes of T cells: CD8-positive cytotoxic T cells (CTL) are restricted to MHC class I. CD4-positive helper T cells (HTL) are restricted to MHC class II. HTL are essential for many features of adaptive immunity: activation of so called “professional antigen-presenting cells” (APCs), immunoglobulin (Ig) class switch, the germinal center reaction and Ig affinity maturation, activation of CTL, immunological memory, regulation of the immune response and others.

MHC molecules collect peptides inside the cell and present them on the cell surface to TCRs of T cells. There are two major classes of MHC, class I recognized by CD8-positive CTL and class II recognized by CD4-positive HTL.

MHC class I molecules consist of a membrane-anchored alpha-chain of 45 kDa and the non-covalently attached b2-microglobulin (b2m) of 12 kDA. Resolution of the 3-dimensional structure by X-ray crystallography (Stern and Wiley 1994) revealed that the alpha-chain possesses a cleft, which is closed at both ends and accommodates peptides from 8 to 11 amino acids length. Class I molecules are ubiquitously expressed, and the peptides they present originate from cytoplasmic proteins. These are degraded by the proteasome, and the resulting peptides are actively transported into the endoplasmatic reticulum (ER). There, with the help of several chaperones, MHC:peptide complexes are formed and transported to the cell surface (Heemels 1995). Thus, MHC class I mirrors the proteome of a cell on its surface and allows T cells to recognize intracellular pathogens or malignant cells.

MHC class II molecules consist of two membrane-anchored proteins (alpha- and beta-chain) of 35 kDa and 30 kDa, respectively. These together form a cleft, open at both ends, which can accommodate peptides of variable length, usually from 12 to 25 amino acids. Despite these differences, class I and II molecules share surprising structural similarity (Stern and Wiley 1994). Class II molecules are only expressed on professional APC including dendritic cells (DC), B-cells and macrophages/monocytes. These cells are specialized in taking up and processing antigens in the endosomal pathway. Immediately after their biosynthesis, class II molecules are complexed by the so-called invariant chain (Ii), which prevents binding of peptides in the ER. When vesicles containing class II:Ii complexes fuse with endosomes containing degradation products of exogenous antigen, Ii is degraded until the MHC binding cleft is only complexed by the so-called CLIP peptide. The latter is with the help of chaperones like HLA-DM exchanged by antigenic peptides (Villadangos 2000). Finally, MHC:peptide complexes are again presented on the surface of APCs, which interact in numerous ways with HTL.

Being both polygenic and extremely polymorphic, the MHC system is highly complex. For the class 1 alpha-chain in humans there are three gene loci termed HLA-A, -B and -C. Likewise, there are three class II alpha-chain loci (DRA, DQA, DPA); for class II beta-chain loci the situation is even more complex as there are four different DR beta-chains (DRB1,2,3,5) plus DQB and DPB. Except the monomorphic DR alpha-chain DRA, each gene locus is present in many different alleles (dozens to hundreds) in the population (Klein 1986). Different alleles have largely distinct binding specificities for peptides. Alleles are designated, for example, HLA-A*0201 or HLA-DRB1*0401 or HLA-DPA*0101/DPB*0401.

T cell epitopes have been identified by a variety of approaches (Van den Eynde 1997). T cell lines and clones have for instance been used to screen cDNA expression libraries for instance in the context of COS cells transfected with the appropriate HLA-molecule. Alternatively, biochemical approaches have been pursued. The latter involved elution of natural ligands from MHC molecules on the surface of target cells, the separation of these peptides by several chromatography steps, analysis of their reactivity with lymphocytes in epitope reconstitution assays and sequencing by mass spectrometry (Wölfel et al. 1994, Cox et al. 1994).

Recently the advent of highly sensitive cytokine detection assays like the IFN-gamma ELIspot allowed using lymphocytes directly ex vivo for screening of overlapping synthetic peptides (Maecker 2001, Kern 2000, Tobery 2001). Primarily, Kern et al. (1999&2000) used arrays of pools of overlapping 9mer peptides to map CD8+ T cell epitopes in vitro. Later, Tobery et al., 2001 modified this approach and demonstrated that pools containing as many as 64 20mer peptides may be used to screen for both CD8+ and CD4+ T cell epitopes in mice. Both these methods were based on the monitoring of antigen-specific response by measuring INF-gamma production either by intracellular staining (Kern et al 2000) or in ELIspot assay (Tobery et al., 2001). By use of mixtures of 15-mers the CD4+ T cell responses are approximately equal to those detected when whole soluble protein was used as an antigen, while—not surprising—the CD8+ T cell responses are significantly higher than the often negligible responses detected with soluble protein stimulation. Furthermore, the CD8+ T cell responses to a mixture of 15 amino acid peptides are similar to those obtained with a mix of 8-12 amino acid peptides, selected to represent known MHC class I minimal epitopes. Most probably peptidases associated with the cell membrane are responsible for “clipping” peptides to optimal length under these circumstances (Maecker et al, 2001).

An interesting alternative is to screen synthetic combinatorial peptide libraries with specific lymphocytes. For instance, a decapeptide library consisting of 200 mixtures arranged in a positional scanning format, has been successfully used for identification of peptide ligands that stimulate clonotypic populations of T cells (Wilson, et al., J. Immunol., 1999, 163:6424-6434).

Many T cell epitopes have been identified by so called “Reverse immunological approaches” Rammensee 1999). In this case the protein giving rise to a potential T cell epitope is known, and its primary sequence is scanned for HLA binding motifs. Typically dozens to hundreds of candidate peptides or even a full set of overlapping peptides are synthesized and tested for binding to HLA molecules. Usually, the best binders are selected for further characterization with regard to their reactivity with T cells. This can for instance be done by priming T cells in vitro or in vivo with the help of HLA transgenic mice.

Hepatitis C Virus (HCV) is a member of the flaviviridiae chronically infecting about 170 million people worldwide. There are at least 6 HCV genotypes and more than 50 subtypes have been described. In America, Europe and Japan genotypes 1, 2 and 3 are most common. The geographic distribution of HCV genotypes varies greatly with genotype 1a being predominant in the USA and parts of Western Europe, whereas 1b predominates in Southern and Central Europe (Bellentani 2000).

HCV is transmitted through the parenteral or percutan route, and replicates in hepatocytes. About 15% of patients experience acute self-limited hepatitis associated with viral clearance and recovery. About 80% of infected persons become chronic carriers. Infection often persists asymptomatically with slow progression for years, however ultimately HCV is a major cause of cirrhosis, end-stage liver disease and liver cancer (Liang 2000). Strength and quality of both HTL and CTL responses determine whether patients recover (spontaneously or as a consequence of therapy) or develop chronic infection (Liang 2000).

Standard therapy of HCV comprises a combination of pegylated interferon-alpha and the antiviral ribavirin. Virologic responses are, depending on the genotype, achieved in about 50% of HCV patients. The low tolerability and the considerable side effects of this therapy clearly necessitate novel therapeutic intervention including therapeutic vaccines (Cornberg 2002). However, presently the detailed understanding of which epitopes in which MHC combination lead to successful immune responses is lacking (Ward 2002). Therefore, a comprehensive analysis of the T-cell response against the entire HCV is required for development of therapeutic epitope-based vaccines.

The HCV virion contains a 9.5-kilobase positive single-strand RNA genome encoding a large single polyprotein of about 3000 amino acids. The latter is processed to at least 10 proteins by both host and HCV-enoded proteolytic activities (Liang 2000). Importantly, the HCV RNA-dependent RNA polymerase is error prone giving rise to the evolution of viral quasispecies and contributing to immune-escape variants (Farci 2000).

It is an object of the present invention to provide a method for screening HCV-peptides for specific MHC molecules, preferably for delivering suitable and specific HCV T cell epitopes selected from a variety of HCV-peptides having unknown specificity for a given MHC molecule and thereby to provide efficient means for preventing and combatting HCV infections.

Therefore the present invention provides a method for isolating HCV-peptides which have a binding capacity to a MHC/HLA molecule or a complex comprising said HCV-peptide and said MHC/HLA molecule which method comprises the following steps:

-   -   providing a pool of HCV-peptides, said pool containing         HCV-peptides which bind to said MHC/HLA molecule and         HCV-peptides which do not bind to said MHC/HLA molecule,     -   contacting said MHC/HLA molecule with said pool of HCV-peptides         whereby a HCV-peptide which has a binding capacity to said         MHC/HLA molecule binds to said MHC/HLA molecule and a complex         comprising said HCV-peptide and said MHC/HLA molecule is formed,     -   detecting and optionally separating said complex from the         HCV-peptides which do not bind to said MHC/HLA molecule and     -   optionally isolating and characterising the HCV-peptide from         said complex.

The present invention also provides a method for isolating HCV T cell epitopes which have a binding capacity to a MHC/HLA molecule or a complex comprising said epitope and said MHC/HLA molecule which method comprises the following steps:

-   -   providing a pool of HCV-peptides, said pool containing         HCV-peptides which bind to a MHC/HLA molecule and HCV-peptides         which do not bind to said MHC/HLA molecule,     -   contacting said MHC/HLA molecule with said pool of HCV-peptides         whereby a HCV-peptide which has a binding capacity to said         MHC/HLA molecule binds to said MHC/HLA molecule and a complex         comprising said HCV-peptide and said MHC/HLA molecule is formed,     -   detecting and optionally separating said complex from the         HCV-peptides which do not bind to said MHC/HLA molecule,     -   optionally isolating and characterising the HCV-peptide from         said complex,     -   assaying said optionally isolated HCV-peptide or said complex in         a T cell assay for T cell activation capacity and     -   providing the optionally isolated HCV-peptide with a T cell         activation capacity as HCV T cell epitope or as complex.

The method according to the present invention enables a screening system for screening binding capacity to specific MHC/HLA molecules. Identifying MHC binding molecules is an important tool for molecular characterisation of pathogens, tumors, etc. It is therefore possible with the present invention to screen a variety (a “pool”) of potential HCV-peptides as ligands at once for their functional affinity towards MHC molecules. Binding affinity towards MHC molecules is also a necessary prerequisite for HCV-peptides intended to be used as T cell epitopes, although not a sufficient one. Suitable HCV T cell epitope candidates have also to be screened and assayed with respect to their T cell activation capacity. The combination of the screening method for binding according to the present invention with a suitable T cell assay therefore provides the method for isolating HCV T cell epitopes according to the present invention wherein such T cell epitopes are identifiable out of a pool of potential HCV-peptides using an MHC binding assay.

In contrast to the prior art, where such assays have always been performed on ligands with known binding/MHC specificity, the methods according to the present invention provide such assays as a screening tool for pools with ligands of unknown specificity. In the prior art such assays have been typically performed on individual single ligands, to test their binding affinity to MHC/HLA molecules. In Kwok et al. (2001) pools of maximally up to 5 overlapping synthetic peptides were used to generate MHC class II tetramers; the latter were then used to stain PBMC for T cells specific for particular MHC class II:peptide complexes which were generated in the binding reaction with the pools of 5 peptides. However, an increase in the number of ligands per pool in such an approach was not regarded as being possible, both for sensitivity and specificity reasons (Novak et al. 2001). A problem with regard to specificity would be the generation of MHC tetramers with more then one binder per tetramer, if more than one binder would be present in the pool. This would preclude staining of T cells, which is used for identification of epitopes in the approach described in the prior art. In strong contrast to that the approach according to the present invention allows the identification of more than on binder out of highly complex mixtures containing more than one binder.

The nature of the pool to be screened with the present invention is not critical: the pools may contain any naturally or not naturally occurring HCV-peptide which a) binds specifically to MHC/HLA molecules and/or b) may be specifically recognized by T cells. The binding properties of the set of HCV-peptides of the pool with respect to MHC molecules is not known; therefore, usually binders and at least a non-binder for a given MHC molecule are contained in the pool. The pool therefore comprises at least ten different HCV-peptides. Practically, pools are used according to the present invention containing significantly more different HCV-peptide species, e.g. 20 or more, 100 or more, 1.000 or more or 10.000 or more. It is also possible to screen larger libraries (with e.g. more than 10⁶, more than 10⁸ or even more than 10¹⁰ different HCV-peptide species). This, however, is mainly dependent on the availability of such HCV-peptide libraries.

Preferred pools of ligands to be used in the method according to the present invention are selected from the group consisting of a pool of peptides, especially overlapping peptides, a pool of protein fragments, a pool of modified peptides, a pool obtained from antigen-presenting cells, preferably in the form of total lysates or fractions thereof, especially fractions eluted from the surface or the MHC/HLA molecules of these cells, a pool comprised of fragments of cells, especially HCV containing cells, tumor cells or tissues, especially from liver, a pool comprised of peptide libraries, pools of (poly)-peptides generated from recombinant DNA libraries, especially derived from pathogens or (liver) tumor cells, a pool of proteins and/or protein fragments from HCV or mixtures thereof.

The HCV-peptides of the pools may be derived from natural sources (in native and/or derivatised form) but also be produced synthetically (e.g. by chemical synthesis or by recombinant technology). If (poly)peptide ligands are provided in the pools, those peptides are preferably generated by peptide synthesizers or by recombinant technology. According to a preferred embodiment, a pool of (poly)peptides may be generated from recombinant DNA libraries, e.g. derived from HCV or HCV containing (tumor) cells, by in vitro translation (e.g. by ribosome display) or by expression through heterologous hosts like E. coli or others.

The nature of the specific MHC molecules (of course also MHC-like molecules are encompassed by this term) to be selected for the present methods is again not critical. Therefore, these molecules may be selected in principle from any species, especially primates like humans (HLA, see below), chimpanzees, other mammals, e.g. maquaques, rabbits, cats, dogs or rodents like mice, rats, guinea pigs and others, agriculturally important animals like cattle, horses, sheep and fish, although human (or “humanized”) molecules are of course preferred for providing vaccines for humans. For providing vaccines for specific animals, especially agriculturally important animals, like cattle, horses, sheep and fish, the use of MHC molecules being specific for these animals is preferred.

Preferred HLA molecules therefore comprise Class I molecules derived from the HLA-A, -B or -C loci, especially A1, A2, A3, A24, A11, A23, A29, A30, A68; B7, B8, B15, B16, B27, B35, B40, B44, B46, B51, B52, B53; Cw3, Cw4, Cw6, Cw7; Class II molecules derived from the HLA-DP, -DQ or -DR loci, especially DR1, DR2, DR3, DR4, DR7, DR8, DR9, DR11, DR12, DR13, DR51, DR52, DR53; DP2, DP3, DP4; DQ1, DQ3, DQ5, DQ6; and non-classical MHC/HLA and MHC/HLA-like molecules, which can specifically bind ligands, especially HLA-E, HLA-G, MICA, MICB, Qa1, Qa2, T10, T18, T22, M3 and members of the CD1 family.

According to a preferred embodiment, the methods according to the present invention is characterised in that said MHC/HLA molecules are selected from HLA class I molecules, HLA class II molecules, non classical MHC/HLA and MHC/HLA-like molecules or mixtures thereof, or mixtures thereof.

Preferably, the optional characterising step of the HCV-peptides of the complex is performed by using a method selected from the group consisting of mass spectroscopy, polypeptide sequencing, binding assays, especially SDS-stability assays, identification of ligands by determination of their retention factors by chromatography, especially HPLC, or other spectroscopic techniques, especially violet (UV), infra-red (IR), nuclear magnetic resonance (NMR), circular dichroism (CD) or electron spin resonance (ESR), or combinations thereof.

According to a preferred embodiment the method of the present invention is characterised in that it is combined with a cytokine secretion assay, preferably with an Elispot assay, an intracellular cytokine staining, FACS or an ELISA (enzyme-linked immunoassays) (see e.g. Current Protocols in Immunology).

Preferred T cell assays comprise the mixing and incubation of said complex with isolated T cells and subsequent measuring cytokine secretion or proliferation of said isolated T cells and/or the measuring up-regulation of activation markers, especially CD69, CD38, or down-regulation of surface markers, especially CD3, CD8 or TCR and/or the measuring up-/down-regulation of mRNAs involved in T cell activation, especially by real-time RT-PCR (see e.g. Current Protocols in Immunology, Current Protocols in Molecular Biology).

Further preferred T cell assays are selected from T cell assays measuring phosphorylation/de-phosphorylation of components downstream of the T cell receptor, especially p56 lck, ITAMS of the TCR and the zeta chain, ZAP70, LAT, SLP-76, fyn, and lyn, T cell assays measuring intracellular Ca⁺⁺ concentration or activation of Ca⁺⁺-dependent proteins, T cell assays measuring formation of immunological synapses, T cell assays measuring release of effector molecules, especially perforin, granzymes or granulolysin or combinations of such T cell assays (see e.g. Current Protocols in Immunology, Current Protocols in Cell Biology).

In order to identify the molecular determinants of immune-protection against HCV a specific method of epitope capturing was applied using synthetic peptides representing the conserved parts of HCV genotypes 1, 2 and 3. Focusing on conserved regions ensures broad applicability of the epitopes. Moreover, these regions probably cannot easily be mutated by the virus, thus minimizing the danger of evolution of immune-escape variants.

With the methods of the present invention novel HCV-epitopes are detected. According to a further aspect, the present invention therefore also provides HCV T cell epitopes identifiable by a method according to the present invention, said T cell epitopes preferably being selected from the group consisting of polypeptides comprising the peptides A120-A124, B25-B30, B46-B48, B84-B92, C106, C113-C114, 1627, 1628, 1629, 1604 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0101, *0401, *0404, *0701 and thus covering at least 45-55% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides 1630, C97, 1547, B94-B98, A272-A276 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0101, *0401, *0701 and thus covering at least 40-50% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides B120, B122, C108, C134, C152 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0101, *0404, *0701 and thus covering at least 45% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides 1606, 1607, 1577, 1578 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0401, *0404, *0701 and thus covering at least 45% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides B50-52, 1623, C130 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0101, *0401, *0404 and thus covering at least 40% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides 1603, C96 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0101, *0701 and thus covering at least 40% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides C191 according to Table 1, being a novel ligand for at least HLA-DRB1*0401, *0701 and thus covering at least 40% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides A216-A224, A242-A244, C92-C93 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0101, *0401 and thus covering at least 35% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptide A174 according to Table 1 or 2, being a novel ligand for at least HLA-DRB1*0404, *0701 and thus covering at least 25-30% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides B32-B38, B100-B102, C135 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0101, *0404 and thus covering at least 20-25% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptide C162 according to Table 1 or 2, being a novel ligand for at least HLA-DRB1*0401, *0404 and thus covering at least 20-25% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides 1618, 1622, 1624, 1546, 1556 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0701 and thus covering at least 25% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides A114, B58, B112-B118, B18-B22, C112, C116, C122, C127, C144, C159-C160, C174, 1558, 1581 according to Table 1 or 2. These peptides are novel ligands for at least HLA-DRB1*0101 and thus covering at least 20% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptide C95, being a novel ligand for at least HLA-DRB1*0401 and thus covering at least 20% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides C129, C157-C158, A254-A258, 1605, C109, C161 according to Table 1 or 2. These peptides comprising novel ligands for at least HLA-DRB1*0404 and thus covering at least 5% of major populations (see Tab. 2).

Preferred polypeptides are selected from the group comprising the peptides 1547, 1555, 1558, 1559, 1560, 1563, 1592, 1604, 1605, 1616, 1621, 1623, 1625, 1627, 1630, 1649, 1650, 1651, 1652, 1654, 1655, 1656 according to Table 1 or 2, these peptides displaying immunogenicity in HLA-DRB1*0401 transgenic mice (see Example II) and thus representing or containing a confirmed HLA class II T-cell epitope binding to at least HLA-DRB1*0401 (see Tab. 3).

Preferred polypeptides are selected from the group comprising the peptides 1545, 1552, 1555, 1558, 1559, 1560, 1577, 1592, 1604, 1605, 1615, 1617, 1621, 1627, 1631, 1632, 1641, 1647, 1650, 1651, 1652, 1653, 1654, 1655 according to Table 1 or 2, these peptides displaying immunogenicity in HLA-A*0201 transgenic mice (see Example II) and thus representing or containing a confirmed HLA class I T-cell epitope binding to at least HLA-A*0201 (see Tab. 3).

Preferred polypeptides which are shown to be HLA-B*0702 epitopes with T-cell activating capacity are selected from the group consisting of polypeptides 1506, 1526, 1547, 1552, 1553, 1555, 1558, 1562, 1563, 1565, 1577, 1578, 1580, 1587, 1592, 1604, 1605, 1621, 1623, 1624, 1627, 1628, 1647, 1650, 1651, 1843 with sequence LPRRGPRL (SEQ ID NO:163) (contained in 1506) and 1838 with sequence SPGALVVGVI (SEQ ID NO:164) (contained in 1587) as minimal HLA-B*0702 epitopes.

Peptides 1526, 1565, 1631 are also shown to be immunogenic in HLA-DRB1*0401 transgenic mice contain known class II epitopes. Peptides 1526, 1553, 1565, 1587, 1623, 1630 are also shown to be immunogenic in HLA-A*0201 transgenic mice contain known A2 epitopes.

Preferred polypeptides are selected from the group comprising the peptides listed in tables 3, 5 and the bold peptides in 7 (“hotspots”).

The preferred polypeptides mentioned above also include all fragments containing the minimal sequence of the epitope, i.e. the 8- or 9-mer being necessary for binding to MHC/HLA molecules.

Preferably, the epitopes or peptides according to the present invention further comprises 1 to 30, preferably 2 to 10, especially 2 to 6, naturally occurring amino acid residues at the N-terminus, the C-terminus or at the N- and C-terminus. For the purposes of the present invention the term “naturally occurring” amino acid residue relates to amino acid residues present in the naturally occurring protein at the specific position, relative to the epitope or peptide. For example, for the HLA-A2 epitope with the amino acid sequence HMWNFISGI (SEQ ID NO:192) contained within peptide ID 1565 (Tab. 1), the naturally occurring amino acid residue at the N-terminus is −K; the three naturally occurring amino acid residues at the C-terminus are −QYL. A “non-naturally occurring” amino acid residue is therefore any amino acid residue being different as the amino acid residue at the specific position relative to the epitope or peptide.

According to a preferred embodiment of the present invention, the present epitopes or peptides further comprise non-naturally occurring amino acid(s), preferably 1 to 1000, more preferred 2 to 100, especially 2 to 20 non-naturally occurring amino acid residues, especially at the N-terminus, the C-terminus or at the N- and C-terminus. Also combinations of non-naturally and naturally occurring amino acid residues are possible under this specific preferred embodiment. The present epitope may also contain modified amino acids (i.e. amino acid residues being different from the 20 “classical” amino acids, such as D-amino acids or S—S bindings of Cys) as additional amino acid residues or in replacement of a naturally occurring amino acid residue.

It is clear that also epitopes or peptides derived from the present epitopes or peptides by amino acid exchanges improving, conserving or at least not significantly impeding the T cell activating capability of the epitopes are covered by the epitopes or peptides according to the present invention. Therefore, the present epitopes or peptides also cover epitopes or peptides, which do not contain the original sequence as derived from a specific strain of HCV, but trigger the same or preferably an improved T cell response. These epitopes are referred to as “heteroclitic”. These include any epitope, which can trigger the same T cells as the original epitope and has preferably a more potent activation capacity of T cells preferably in vivo or also in vitro. Also the respective homologous epitopes from other strains of HCV are encompassed by the present invention.

Heteroclitic epitopes can be obtained by rational design i.e. taking into account the contribution of individual residues to binding to MHC/HLA as for instance described by Ramensee et al. 1999 or Sturniolo et al. 1999, combined with a systematic exchange of residues potentially interacting with the TCR and testing the resulting sequences with T cells directed against the original epitope. Such a design is possible for a skilled man in the art without much experimentation.

Another possibility includes the screening of peptide libraries with T cells directed against the original epitope. A preferred way is the positional scanning of synthetic peptide libraries. Such approaches have been described in detail for instance by Blake et al 1996 and Hemmer et al. 1999 and the references given therein.

As an alternative to epitopes represented by the cognate HCV derived amino acid sequence or heteroclitic epitopes, also substances mimicking these epitopes e.g. “peptidemimetica” or “retro-inverso-peptides” can be applied.

Another aspect of the design of improved epitopes is their formulation or modification with substances increasing their capacity to stimulate T cells. These include T helper cell epitopes, lipids or liposomes or preferred modifications as described in WO 01/78767.

Another way to increase the T cell stimulating capacity of epitopes is their formulation with immune stimulating substances for instance cytokines or chemokines like interleukin-2, -7, -2, -18, class I and II interferons (IFN), especially IFN-gamma, GM-CSF, TNF-alpha, flt3-ligand and others.

According to a further aspect, the present invention is drawn to the use of a HCV epitope or HCV peptide according to the present invention for the preparation of a HLA restricted vaccine for treating or preventing hepatitis C virus (HCV) infections.

The invention also encompasses the use of an epitope according to the present invention for the preparation of a vaccine for treating or preventing preventing hepatitis C virus (HCV) infections.

Consequently, the present invention also encompasses a vaccine for treating or preventing hepatitis C virus (HCV) infections comprising an epitope according to the present invention.

Furthermore, also a HLA specific vaccine for treating or preventing hepatitis C virus (HCV) infections comprising the epitopes or peptides according to the present invention is an aspect of the present invention.

Preferably, such a vaccine further comprises an immunomodulating substance, preferably selected from the group consisting of polycationic substances, especially polycationic polypeptides, immunomodulating nucleic acids, especially deoxyinosine and/or deoxyuracile containing oligodeoxynucleotides, or mixtures thereof.

Preferably the vaccine further comprises a polycationic polymer, preferably a polycationic peptide, especially polyarginine, polylysine or an antimicrobial peptide.

The polycationic compound(s) to be used according to the present invention may be any polycationic compound, which shows the characteristic effect according to the WO 97/30721. Preferred polycationic compounds are selected from basic polypeptides, organic polycations, basic polyaminoacids or mixtures thereof. These polyaminoacids should have a chain length of at least 4 amino acid residues. Especially preferred are substances containing peptidic bounds, like polylysine, polyarginine and polypeptides containing more than 20%, especially more than 50% of basic amino acids in a range of more than 8, especially more than 20, amino acid residues or mixtures thereof. Other preferred polycations and their pharmaceutical compositions are described in WO 97/30721 (e.g. polyethyleneimine) and WO 99/38528. Preferably these polypeptides contain between 20 and 500 amino acid residues, especially between 30 and 200 residues.

These polycationic compounds may be produced chemically or recombinantly or may be derived from natural sources.

Cationic (poly)peptides may also be polycationic anti-bacterial microbial peptides. These (poly)peptides may be of prokaryotic or animal or plant origin or may be produced chemically or recombinantly. Peptides may also belong to the class of defensines. Such host defense peptides or defensines are also a preferred form of the polycationic polymer according to the present invention. Generally, a compound allowing as an end product activation (or down-regulation) of the adaptive immune system, preferably mediated by APCs (including dendritic cells) is used as polycationic polymer.

Especially preferred for use as polycationic substance in the present invention are cathelicidin derived antimicrobial peptides or derivatives thereof (WO 02/13857), incorporated herein by reference), especially antimicrobial peptides derived from mammal cathelicidin, preferably from human, bovine or mouse, or neuroactive compounds, such as (human) growth hormone (as described e.g. in WO01/24822).

Polycationic compounds derived from natural sources include HIV-REV or HIV-TAT (derived cationic peptides, antennapedia peptides, chitosan or other derivatives of chitin) or other peptides derived from these peptides or proteins by biochemical or recombinant production. Other preferred polycationic compounds are cathelin or related or derived substances from cathelin, especially mouse, bovine or especially human cathelins and/or cathelicidins. Related or derived cathelin substances contain the whole or parts of the cathelin sequence with at least 15-20 amino acid residues. Derivations may include the substitution or modification of the natural amino acids by amino acids, which are not among the 20 standard amino acids. Moreover, further cationic residues may be introduced into such cathelin molecules. These cathelin molecules are preferred to be combined with the antigen/vaccine composition according to the present invention. However, these cathelin molecules surprisingly have turned out to be also effective as an adjuvant for a antigen without the addition of further adjuvants. It is therefore possible to use such cathelin molecules as efficient adjuvants in vaccine formulations with or without further immunactivating substances.

Another preferred polycationic substance to be used according to the present invention is a synthetic peptide containing at least 2 KLK-motifs separated by a linker of 3 to 7 hydrophobic amino acids, especially L (WO 02/32451, incorporated herein by reference).

The immunomodulating (or:immunogenic) nucleic acids to be used according to the present invention can be of synthetic, prokaryotic and eukaryotic origin. In the case of eukaryotic origin, DNA should be derived from, based on the phylogenetic tree, less developed species (e.g. insects, but also others). In a preferred embodiment of the invention the immunogenic oligodeoxynucleotide (ODN) is a synthetically produced DNA-molecule or mixtures of such molecules. Derivatives or modifications of ODNs such as thiophosphate substituted analogues (thiophosphate residues substitute for phosphate) as for example described in US patents U.S. Pat. No. 5,723,335 and U.S. Pat. No. 5,663,153, and other derivatives and modifications, which preferably stabilize the immunostimulatory composition(s) but do not change their immunological properties, are also included. A preferred sequence motif is a six base DNA motif containing an (unmethylated) CpG dinucleotide flanked by two 5′ purines and two 3′ pyrimidines (5′-Pur-Pur-C-G-Pyr-Pyr-3′). The CpG motifs contained in the ODNs according to the present invention are more common in microbial than higher vertebrate DNA and display differences in the pattern of methylation. Surprisingly, sequences stimulating mouse APCs are not very efficient for human cells. Preferred palindromic or non-palindromic ODNs to be used according to the present invention are disclosed e.g. in Austrian Patent applications A 1973/2000, A 805/2001, EP 0 468 520 A2, WO 96/02555, WO 98/16247, WO 98/18810, WO 98/37919, WO 98/40100, WO 98/52581, WO 98/52962, WO 99/51259 and WO 99/56755 all incorporated herein by reference. Apart from stimulating the immune system certain ODNs are neutralizing some immune responses. These sequences are also included in the current invention, for example for applications for the treatment of autoimmune diseases. ODNs/DNAs may be produced chemically or recombinantly or may be derived from natural sources. Preferred natural sources are insects.

Alternatively, also nucleic acids based on inosine and cytidine (as e.g. described in the WO 01/93903) or deoxynucleic acids containing deoxy-inosine and/or deoxyuridine residues (described in WO 01/93905 and PCT/EP 02/05448, incorporated herein by reference) may preferably be used as immunostimulatory nucleic acids for the present invention.

Of course, also mixtures of different immunogenic nucleic acids may be used according to the present invention.

Preferably, the present vaccine further comprises a pharmaceutically acceptable carrier.

According to a further preferred embodiment, the present vaccine comprises an epitope or peptide which is provided in a form selected from peptides, peptide analogues, proteins, naked DNA, RNA, viral vectors, virus-like particles, recombinant/chimeric viruses, recombinant bacteria or dendritic cells pulsed with protein/peptide/RNA or transfected with DNA comprising the epitopes or peptides.

According to a further aspect, the present invention is drawn to T cells, a T cell clone or a population (preparation) of T cells specifically recognizing any HCV epitope or peptide according to the present invention, especially a HCV epitope as described above. A preferred application of such T cells is their expansion in vitro and use for therapy of patients e.g. by adoptive transfer. Therefore, the present invention also provides the use of T cells, a T cell clone or a population (preparation) of T cells for the preparation of a composition for the therapy of HCV patients.

Such T cells (clones or lines) according to the present invention, specifically those recognizing the aforementioned HCV peptides are also useful for identification of heteroclitic epitopes, which are distinct from the originally identified epitopes but trigger the same T cells.

Such cells, compositions or vaccines according to the present invention are administered to the individuals in an effective amount.

According to a further aspect, the present invention also relates to the use of the peptides with formulae QRKTKRNTN (SEQ ID NO:167), QRKTKRNT (SEQ ID NO:166), or 1615, 1616, 1617 in particular 9meric peptides derived from the latter 3 peptides with formulae SAKSKFGYG (SEQ ID NO:193), SAKSKYGYG (SEQ ID NO:194), or SARSKYGYG (SEQ ID NO:195) as HLA-B*08 epitopes, especially for the preparation of a pharmaceutical preparation for a HLA-B*08 specific vaccine; the use of the peptides with the formulae RKTKRNTNR (SEQ ID NO:170) as HLA-B*2705 epitope, especially for the preparation of a pharmaceutical preparation for a HLA-B*2705 specific vaccine; and the use of the peptides with the formulae ARLIVFPDL (SEQ ID NO:1053) as HLA-B*2705 and HLA-B*2709 specific vaccine. Further, it also relates to the use of the hotspot epitopes selected from the group of peptides 1835, 84EX, 87EX, 89EX, 1426, 1650, 1836, 1846, 1651, 1800, 1799, C114, 1827, C112, C114EX, 1827EX, 1798, 1604, 1829, 1579, 1624, 1848, 1547, A1A7, A122EX, A122, 1825, A241, B8B38, C70EX, C92, C97, C106, and C134 according to table 7 for the preparation of a vaccine comprising synthetic peptides, recombinant protein and/or DNA constitutes of such epitopes.

In particular, two or more epitope hotspots can be combined, with or without linker sequences. Preferred linker sequences consist for instance of 3 to 5 glycine, or alanine or lysine residues. This may be achieved by peptide synthesis, However, combination of hotspots may result in quite long polypeptides. In this case, cloning DNA encoding for such constructs and expressing and purifying the corresponding recombinant protein is an alternative. Such recombinant proteins can be used as antigens, which in combination with the right adjuvant (IC31, pR, . . . ) can elicit T-cell responses against all the epitopes they harbor. At the same time, such artificial polypeptides are devoid of the activities (enzymatic, toxic, immuno-suppressive, . . . ), the natural HCV antigens may possess.

There are several other ways of delivering T-cell epitope hotspots or combinations thereof. These include: recombinant viral vectors like vaccinia virus, canary pox virus, adenovirus; self-replicating RNA vectors; “naked DNA” vaccination with plasmids encoding the hotspots or combination thereof; recombinant bacteria (e.g. Salmonella); dendritic cells pulsed with synthetic peptides, or recombinant protein, or RNA or transfected with DNA, each encoding T-cell epitope hotspots or combinations thereof.

The invention will be explained in more detail by way of the following examples and drawing figures, to which, however it is not limited.

FIG. 1 shows 40 peptide mixtures each containing up to 20 HCV derived 15- to 23mer peptides.

FIG. 2 shows the Epitope Capture approach using peptide pools and empty DRB1*0401 molecules.

FIG. 3 shows the Epitope Capture approach using peptide pools and empty DRB1*0404 molecules.

FIG. 4 shows binding of individual peptides to DRB1*0401.

FIG. 5 shows binding of individual peptides to DRB1*0404.

FIG. 6 shows binding of individual peptides to DRB1*0101.

FIG. 7 shows peptides binding to DRB1*0701.

FIG. 8 shows mouse IFN-gamma ELIspot with splenocytes or separated CD8+ or CD4+ cells from HLA-DRB1*0401 tg mice vaccinated with Ipep1604+IC31.

FIG. 9 shows mouse IFN-gamma ELIspot with splenocytes or separated CD8+ or CD4+ cells from HLA-A*0201 tg mice vaccinated with Ipep1604+IC31.

FIG. 10 shows mouse IFN-gamma ELIspot with splenocytes or separated CD8+ or CD4+ cells from HLA-B*0702 tg mice vaccinated with Ipep1604+IC31.

EXAMPLES

General description of the examples:

The present examples show the performance of the present invention on a specific pathogen hepatitis C virus (HCV).

In the first part the method according to the present invention was applied, which is based on the use of “empty HLA molecules”. These molecules were incubated with mixtures of potential HCV derived peptide ligands, screening for specific binding events. The possibility to use highly complex mixtures allows a very quick identification of the few binders out of hundreds or even thousands of potential ligands. This is demonstrated by using HLA-DRB1*0101, -DRB1*0401, -DRB1*0404, -DRB1*0701 molecules and pools of overlapping 15- to 23mers. Importantly, this analysis using multiple different HLA-alleles allows identifying promiscuous ligands capable to binding to more than one HLA allele. Promiscuous T-cell epitopes are particularly valuable components of epitope-based vaccines. They enable treating a higher portion of a population than epitopes restricted to one HLA allele.

The same process can be applied for class I molecules and peptides of appropriate length i.e. 8 to 11-mers. The ligand-pools can be synthetic overlapping peptides. Another possibility is to digest the antigen in question enzymatically or non-enzymatically. The latter achieved by alkali-hydrolysis generates all potential degradation products and has been successfully used to identify T cell epitopes (Gavin 1993). Enzymatic digestions can be done with proteases. One rational way would further be to use proteases involved in the natural antigen-processing pathway like the proteasome for class I restricted epitopes (Heemels 1995) or cathepsins for class II restricted epitopes (Villadangos 2000). Ligand pools could also be composed of naturally occurring ligands obtained for instance by lysis of or elution from cells carrying the respective epitope. In this regard it is important to note that also non-peptide ligands like for instance glycolipids can be applied. It is known that nonclassical class I molecules, which can be encoded by the MHC (e.g. HLA-G, HLA-E, MICA, MICB) or outside the MHC (e.g. CD1 family) can present various non-peptide ligands to lymphocytes (Kronenberg 1999). Use of recombinant “empty” nonclassical class I molecules would allow binding reactions and identification of binders in similar manner as described here.

After rapid identification of ligands capable of binding to HLA molecules the process according to the present invention also offers ways to characterize directly specific T cell responses against these binders. One possibility is to directly use the isolated HLA:ligand complex in a so called “synthetic T cell assay”. The latter involves antigen-specific re-stimulation of T cells by the HLA:ligand complex together with a second signal providing co-stimulation like activation of CD28 by an activating antibody. This assay can be done in an ELIspot readout.

Another possibility is the immunization of HLA-transgenic mice to prove immunogenicity of ligands identified by the Epitope Capture approach as demonstrated in Example II.

Materials & Methods

Peptides

In order to identify conserved regions between HCV genotypes 1, 2 and 3, about 90 full genomes publicly available through Genebank were aligned. In total, 43% of the coding region of HCV was found to be conserved in at least 80% of clinical isolates. In cases, where at a certain position consistently two distinct amino acids (eg. arginine or lysine) were found, both variants were considered for analysis. Altogether 148 conserved regions, longer than 8 amino acids were identified. Conserved region were spanned by ˜500 fifteen amino acid residue (15mer) peptides, each peptide overlapping its precursor by 14 out of 15 amino acids. Conserved regions between 8 and 14 amino acids long were covered by further 80 (non-overlapping) 15mers. 15mers were synthesized using standard F-moc chemistry in parallel (288 at a time) on a Syro II synthesizer (Multisyntech, Witten, Germany). Each fourth 15mer was checked by mass spectrometry. 15mers were applied for experiments without further purification. In addition 63 peptides of 16-xx aa were synthesized using standard F-moc chemistry on an ABI 433A synthesizer (Applied Biosystems, Weiterstadt, Germany) and purified by RP-HPLC (Biocut 700E, Applied Biosystems, Langen, Germany) using a C18 column (either ODS ACU from YMC or 218TP, Vydac). Purity and identity were characterized by MALDI-TOF on a Reflex III mass-spectrometer (Bruker, Bremen, Germany). Peptides were solubilized in 100% DMSO at ˜10 mg/ml (˜5 mM). Stocks of peptide pools (20 peptides each) were made in 100% DMSO at a final concentration of 0.5 mg/ml (˜0.25 mM) for each peptide. All peptides used in the present invention are listed in Table 1. Peptides YAR (YARFQSQTTLKQKT (SEQ ID NO:196)), HA (PKYVKQNTLKLAT (SEQ ID NO:197)), P1 (GYKVLVLNPSVAAT (SEQ ID NO:198)), P2 (HMWNFISGIQYLAGLSTLPGNPA (SEQ ID NO:199)), P3 (KFPGGGQIVGVYLLPRRRGPRL (SEQ ID NO:200)), P4 (DLMGYIPAV (SEQ ID NO:201)) and CLIP (KLPKPPKPVSKMRMATPLLMQALPM (SEQ ID NO:202)) were used as control peptides in binding assays.

Epitope Capture and Peptide Binding Assay

Soluble HLA class II DRA1*0101/DRB1*0101/Ii, DRA1*0101/DRB1*0401/Ii, DRA1*0101/DRB1*0404/Ii and DRA1*0101/DRB1*0701/Ii molecules were expressed in SC-2 cells and purified as described in Aichinger et al., 1997. In peptide binding reactions soluble DRB1*0101, DRB1*0401, DRB1*0404 molecules were used in a concentration of ˜0.5 μM, and each single peptide was added in 10-fold molar excess (5 μM) if not mentioned differently. The concentration of DMSO in the binding reaction did not exceed 4%. The reaction was performed in PBS buffer (pH 7.4) at room temperature for 48 hours in the presence of a protease inhibitor cocktail (Roche) and 0.1% octyl-beta-D-glucopyranoside (Sigma). Peptide binding was evaluated in an SDS-stability assay (Gorga et al., 1987): trimeric HLA class II alpha:beta:peptide complexes are resistant to SDS and consequently appear as ˜60 kDa band in SDS-PAGE Western blot analysis. Individual HLA class II alpha- and beta-chains not stabilized by bound peptide migrate as ˜35 kDa and ˜25 kDa bands, respectively. Briefly, HLA-peptide complexes were treated with 1% SDS at room temperature and resolved by SDS-PAGE run with 20 mA for approximately 2.5 hours at room temperature. Protein was transferred onto PVDF membrane by electroblotting, and stained with anti-alpha-chain TAL.1B5 or/and beta-chain MEM136 antibodies. For detection of Western-blot signals ECL solutions (Amersham) were used. For DRB1*0101 molecules HA and P1 peptides were used as controls for evaluation of strong binding, P2 peptide for intermediate binding and YAR as a negative control. For DRB1*0401 the strongest binding controls were YAR and HA peptides, while P1 and P2 served as an intermediate and weak binder, respectively. In the case of DRB1*0404 molecules P1 and P2 peptides were used to estimate strong binding, YAR peptide to control intermediate binding and HA peptide as an negative control. The binding affinities to DRB1*0701 were test by a peptide-competition assay (Reay et al., 1992). Briefly, binding of the biotinylated CLIP peptide with high affinity (reference peptide) has been used for monitoring of HLA:peptide complex formation. A testing peptide added to the binding reaction at an equimolar concentration to CLIP peptide could compete out CLIP when its affinity is higher or inhibit binding for 50% if its affinity is equal to affinity of CLIP. In the case of lower affinity peptides they should be added in excess to the reference peptide to compete for occupancy of HLA binding grove. The values of the concentration of competitor peptides required for 50% inhibition of reference peptide (biotinylated CLIP) binding (IC₅₀) can be used for evaluation of peptide binding affinities. Alternatively, comparing of the amount of reference peptide bound to HLA molecules in the presence or absence of competitor peptide one can determine the binding activity of the peptide of interest. In the present peptide-competition assay conditions of peptide binding were similar to described above. DRB1*0701 molecules were used in a concentration of ˜0.5 μM and biotinylated CLIP was added to all samples in the final concentration of 2 μM. Competitor peptides were added in three different concentrations: 2 nM, 20 μM and 200 μM. Binding reaction was performed in PBS buffer (pH 7.4) for 18 hours at 37° C. The amount of biotinylated CLIP associated with soluble DRB1*0701 molecules was determined by ELISA. Briefly, MaxiSorp 96-well plates (Nunc, Denmark) were coated with mouse anti-DR antibody L243 by overnight incubation with 50 μl of 10 μg/ml dilution in PBS at 4° C. Non-specific binding to wells a was blocked by incubation with T-PBS containing 3% of BSA for 2 hours at 37° C. and binding reactions were then “captured” for 2 hours at room temperature. Following extensive washing, HLA-assosiated peptide complexes were detected using alkaline phosphatase-streptavidin (Dako) and Sigma 104 phosphatase substrate. A microplate reader (VICTOR) was used to monitor optical density at 405 nm. Non-biotinylated CLIP, P1 and P2 peptides were used as positive controls to evaluate strong binding. Peptide P3 and P4 served as a weakly binding and non-binding control, respectively.

Immunization of HLA-Transgenic Mice

Immunogenicity of synthetic HCV-derived peptides was tested in HLA-DRB1*0401- and HLA-A*0201-transgenic mice as follows: Groups of 3 mice (female, 8 weeks of age) were injected subcutaneously into the flank (in total 100 μg of peptide +30 μg oligodinucleotide CpI (Purimex, Göttingen, Germany) per mouse). One week after the vaccination, spleens were removed and the splenocytes were activated ex vivo with the peptide used for vaccination and an irrelevant negative control peptide to determine IFN-gamma-producing specific cells (mouse ELISpot assay).

Mouse splenocyte ELIspot assay for single cell IFN-gamma release ELISpot plates (MAHA S4510, Millipore, Germany) were rinsed with PBS (200 μl/well), coated with anti-mouse IFN-gamma mAb (clone R46A2; 100 μl/well of 5 μg/ml in 0.1 M NaHCO₃, pH 9.2-9.5) and incubated overnight at 4° C. Plates were washed four times with PBS/0.1% Tween 20 and incubated with PBS/1% BSA (200 μl/well) at room temperature for 2 h to block nonspecific binding. Spleen cells from vaccinated mice were prepared and plated at 1×10⁶-3×10⁵ cells/well and incubated overnight at 37° C./5% CO₂ either in the presence of the immunizing antigen (peptide), control peptides or with medium alone. Subsequently, plates were washed four times and incubated with biotinylated anti-mouse IFN-gamma mAb (clone AN18.17.24, 100 μl/well of 2 μg/ml in PBS/1% BSA) for 2 h at 37° C. After washing, streptavidin-peroxidase (Roche Diagnostics, Vienna, Austria) was added (1/5000 in PBS, 100 μl/well) and plates were incubated at room temperature for 2 additional hours. Subsequently, substrate was added to the washed plates (100 μl/well of a mixture of 10 ml 100 mM Tris pH 7.5 supplemented with 200 μl of 40 mg/ml DAB stock containing 50 μl of 80 mg/ml NiCl₂ stock and 5 μl of 30% H₂O₂). The reaction was stopped after 20-30 minutes by washing the plates with tap water. Dried plates were evaluated with an ELISpot reader (BIOREADER 2000, BioSys, Karben, Germany).

IFN-Gamma ELIspot with Human PBMC

PBMC from HCV RNA-negativ therapy responders or subjects spontaneously recovered were collected and HLA-typed serologically. Whole blood was collected in ACD Vacutainer tubes (Becton Dickinson Europe, Erembodegem, Germany). PBMC were isolated on Lymphoprep (Nycomed Pharma AS, Oslo, Norway) using Leuco-sep tubes (Greiner, Frickenhausen, Germany), washed 3× with PBS (Invitrogen Life Technologies (formerly GIBCOBRL), Carlsbad, Calif., USA) and resuspended at a concentration of 2×10⁷/ml in freezing medium consisting of 4 parts RPMI 1640 supplemented with 1 mM sodium pyruvate, 2 mM L-glutamine, 0.1 mM non-essential amino acids, 50 μM 2-mercaptoethanol (all from Invitrogen Life Technologies), 9 parts foetal bovine serum (FCS; from PAA, Linz, Austria) and 1 part DMSO (SIGMA, Deisenhofen, Germany). PBMC were stored over night in 1° C. freezing containers (Nalgene Nunc International, Rochester, N.Y., USA) at −80° C. and then transferred into liquid nitrogen. The ELIspot assay was essentially done as described (Lalvani et al.). Briefly, Multi Screen 96-well filtration plates MAIP S4510 (Millipore, Bedford, Mass.) were coated with 10 μg/ml (0,75 μg/well) anti-human IFN-g monoclonal antibody (Mab) B140 (Bender Med Systems, Vienna, Austria) over night at 4° C. Plates were washed 2 times with PBS (Invitrogen Life Technologies) and blocked with ELIspot medium (RPMI 1640 supplemented with 1 mM sodium pyruvate, 2 mM L-glutamine, 0.1 mM non-essential amino acids, 50 μM 2-mercaptoethanol (all from Invitrogen Life Technologies) and 10% human serum type AB (PAA, Linz, Austria). Cryo-preserved PBMC were thawed quickly in a 37° C. water bath, washed 1× with ELISPOT medium and incubated overnight (37° C., 5% CO₂). The next day cells were plated at 200,000 PBMC/well and co-cultivated with either individual peptides (10 μg/ml) or peptide pools (each peptide at a final concentration of 5 μg/ml) for 20 hrs. After removing cells and washing 6 times with wash buffer (PBS; 0,1% Tween 20 from SIGMA), 100 μl of a 1:10000 dilution (0.015 μg/well) of the biotinylated anti-human IFN-γ MAb B308-BT2 (Bender Med Systems), was added for an incubation of 2 hrs at 37° C. or alternatively for over night at 4° C. After washing, Streptavidin-alkaline phosphatase (DAKO, Glostrup, Denmark) was added at 1.2 μg/ml for 1 hr at 37° C. The assay was developed by addition of 100 μl/well BCIP/NBT alkaline phosphatase substrate (SIGMA).

In Vitro Priming of Human PBMCs

Human PBMCs are repeatedly stimulated with antigen (peptide or peptide mixture) in the presence of IL-2 and IL-7. This leads to the selective oligoclonal expansion of antigen-specific T cells. Responses against individual epitopes can be assessed for instance by IFN-γ ELIspot assays. Freshly thawed PBMCs were cultured in 6 well plates (2-4×10⁶/mL viable cells) in RPMI-1640 (GibcoBRL), 1% non-essential amino acids (GibcoBRL, cat# 11140-035), 1% Penicillin (10,000 U/ml)-Streptomycin (10,000 μg/ml) (GibcoBRL, cat#15140-122), 1% L-Glutamine (GibcoBRL), 0.1% beta-mercapto-ethanol (GibcoBRL), 1% Na-pyruvate (GibcoBRL), plus 10% Human AB serum (PAA, Linz, Austria). Peptides (10 μM each) were added to each well. rhIL-7 (Strathmann Biotech) was added at 10 ng/mL final concentration. 20-30 U/mL rhIL-2 (Strathmann Biotech) were added on day 4. On day 10, all cells were removed from plates, washed once in media (as above), and counted. For the next cycle of in vitro priming, viable cells were co-cultivated with autologous gamma irradiated (1.2 gray/min, for 20 minutes) PBMC as feeders (plated at 100,000 per well) and peptides, rh-IL-2 as described above. ELIspot was done as described above, except that 200,000 responder cells (pre-stimulated for 2 rounds of in vitro priming) were used together with 60,000 autologous irradiated responder cells.

Example I Rapid Identification of Promiscuous HLA-Binding Peptides from Hcv by Measuring Peptide Pools Arrayed in Matrix Format

To span conserved regions within the HCV polyprotein more than 640 peptides were synthesized (Table 1). For rapid identification of HLA ligands and novel T-cell epitopes, 40 peptide pools each containing 20 single peptides were prepared. The pools were constructed in a way that each peptide was present in 2 pools (matrix format). This allows identification of reactive peptides at the crossover points of row- and column mixtures (FIG. 1 HCV peptide matrix). TABLE 1 Synthetic peptides derived from conserved regions of HCV PEP- PEP- PEP- PEP- TIDE SEQ TIDE SEQ TIDE SEQ TIDE SEQ ID ID PEPTIDE ID ID PEPTIDE ID ID PEPTIDE ID ID PEPTIDE A1 203 MSTNPKPQRKTKRNT A79 360 HRSRNVGKVIDTLTC A157 517 CTVNYTIFKIRMYVG A235 674 ADGGCSGGAYDIIIC A2 204 STNPKPQRKTKRNTN A80 361 RSRNVGKVIDTLTCG A158 518 TVNYTIFKIRMYVGG A236 675 DGGCSGGAYDIIICD A3 205 TNPKPQRKTKRNTNR A81 362 SRNVGKVIDTLTCGF A159 519 VNYTIFKIRMYVGGV A237 676 GGCSGGAYDIIICDE A4 206 NPKPQRKTKRNTNRR A82 363 RNVGKVIDTLTCGFA A160 520 NYTIFKIRMYVGGVE A238 677 GCSGGAYDIIICDEC A5 207 PKPQRKTKRNTNRRP A83 364 NVGKVIDTLTCGFAD A161 521 YTIFKIRMYVGGVEH A239 678 CSGGAYDIIICDECH A6 208 KPQRKTKRNTNRRPQ A84 365 VGKVIDTLTCGFADL A162 522 TIFKIRMYVGGVEHR A240 679 SGGAYDIIICDECHS A7 209 PQRKTKRNTNRRPQD A85 366 TLTCGFADLMGYIPV A163 523 IFKIRMYVGGVEHRL A241 680 TTILGIGTVLDQAET A8 210 QRKTKRNTNRRPQDV A86 367 LTCGFADLMGYIPVV A164 524 LPALSTGLIHLHQNI A242 681 TILGIGTVLDQAETA A9 211 RKTKRNTNRRPQDVK A87 368 TCGFADLMGYIPVVG A165 525 PALSTGIHLHQNIV A243 682 ILGIGTVLDQAETAG A10 212 KTKRNTNRRPQDVKF A88 369 CGFADLMGYIPVVGA A166 526 ALSTGLIHLHQNIVD A244 683 LGIGTVLDQAETAGA A11 213 TKRNTNRRPQDVKFP A89 370 GFADLMGYIPVVGAP A167 527 LSTGIHLHQNIVDV A245 684 GIGTVLDQAETAGAR A12 214 KRNTNRRPQDVKFPG A90 371 FADLMGYIPVVGAPL A165 528 STGLIHLHQNIVDVQ A246 685 IGTVLDQAETAGARL A13 215 RNTNRRPQDVKFPGG A91 372 ADLMGYIPVVCAPLG A169 529 TQLIHLHQNIVDVQY A247 686 GTVLDQAETAGARLV A14 216 NTNRRPQDVKFPGGG A92 373 DLMGYIPVVGAPLGG A170 530 GLIHLHQNIVDVQYL A248 687 TVLDQAETAGARLVV A15 217 TNRRPQDVKFPGGGQ A93 374 ARALAHGVRVLEDGV A171 531 LIHLHQNIVDVQYLY A249 688 VLDQAETAGARLVVL A16 218 NRRPQDVKFPGGGQI A94 375 RALAHGVRVLEDGVN A172 532 IHLHQNIVDVQYLYG A250 689 LDQAETACARLVVLA A17 219 RRPQDVKFPGGGQIV A95 376 ALAHGVRVLEDGVNY A173 533 LPALSTGLLHLHQNI A251 690 DQAETAGARLVVLAT A18 220 RPQDVKFPGGGQIVG A96 377 LAHGVRVLEDGVNYA A174 534 PALSTGLLHLHQNIV A252 691 QAETAGARLVVLATA A19 221 PQDVKFPGGGQIVGG A97 378 AHGVRVLEDGVNYAT A175 535 ALSTGLLHLHQNIVD A253 692 AETAGARLVVLATAT A20 222 QDVKFPGGGQIVGGV A98 379 HGVRVLEDGVNYATG A176 536 LSTGLLHLHQNIVDV A254 693 ETAGARLVVLATATP A21 223 DVKFPGGGQIVGGVY A99 380 GVRVLEDGVNYATGN A177 537 STGLLHLHQNIVDVQ A255 694 TAGARLVVLATATPP A22 224 VKFPGGGQIVGGVYL A100 381 VRVLEDGVNYATGNL A178 538 TGLLHLHQNIVDVQY A256 695 AGARLVVLATATPPG A23 225 KFPGGGQIVGGVYLL A101 382 RVLEDGVNYATGNLP A179 539 GLLHLHQNIVDVQYM A257 696 GARLVVLATATPPGS A24 226 FPGGGQIVGGVYLLP A102 383 VLEDGVNYATGNLPG A180 540 LLHLHQNIVDVQYMY A258 697 ARLVVLATATPPGSV A25 227 PGGGQIVGGVYLLPR A103 384 LEDGGVNYATGNLPGC A181 541 LHLHQNIVDVQYMYG A259 698 RLVVLATATPPGSVT A26 228 GGGQIVGGVYLLPRR A104 385 EDGVNYATGNLPGCS A182 542 HLHAPTGSGKSTKVP A260 699 TSILGIGTVLDQAET A27 229 GGQIVGGVYLLPRRG A105 386 DGVNYATGNLPGCSF A183 543 LHAPTGSGKSTKVPA A261 700 SILGIGTVLDQAETA A28 230 GQIVGGVYLLPRRGP A106 387 GVNYATGNLPGCSES A184 544 HAPTGSGKSTKVPAA A262 701 LGIGTVLDQAETAGV A29 231 QIVGGVYLLPRRGPR A107 388 VNYATGNLPGCSFSI A185 545 APTGSGKSTKVPAAY A263 702 GIGTVLDQAETAGVR A30 232 IVGGVYLLPRRGPRL A108 389 NYATGNLPGCSFSIF A186 546 PTGSGKSTKVPAAYA A264 703 IGTVLDQAETAGVRL A31 233 VGGVYLLPRRGPRLG A109 390 YATGNLPGCSFSIFL A187 547 TGSGKSTKVPAAYAA A265 704 GTVLDQAETAGVRLT A32 234 GGVYLLPRRGPRLGV A110 391 ATGNLPGCSFSIFLL A188 548 GSGKSTKVPAAYAAQ A266 705 TVLDQAETAGVRLTV A33 235 GVYLLPRRGPRLGVR A111 392 TGNLPGCSFSIFLLA A189 549 SGKSTKVPAAYAAQG A267 706 VLDQAETAGVRLTVL A34 236 VYLLPRRGPRLGVRA A112 393 GNLPGCSFSIFLLAL A190 550 GKSTKVPAAYAAQGY A268 707 LDQAETAGVRLTVLA A35 237 YLPRRGPRLGVRAT A113 394 NLPGCSFSIFLLALL A191 551 KSTKVPAAYAAQGYK A269 708 DQAETAGVRLTVLAT A36 238 LLPRRGPRLGVRATR A114 395 LPGCSFSIFLLALLS A192 552 STKVPAAYAAQGYKV A270 709 QAETAGVRLTVLATA A37 239 LPRRGPRLGVRATRK A115 396 PGCSFSIFLLALLSC A193 553 TKVPAAYAAQGYKVL A271 710 AETAGVRLTVLATAT A38 240 PRRGPRLGVRATRKT A116 397 IQLINTNGSWHINRT A194 554 KVPAAYAAQGYKVLV A272 711 ETAGVRLTVLATATP A39 241 RRGPRLGVRATRKTS A117 398 QLINTNGSWHINRTA A195 555 VPAAYAAQGYKVLVL A273 712 TAGVRLTVLATATPP A40 242 RGPRLGVRATRKTSE A118 399 LINTNGSWHINRTAL A196 556 PAAYAAQGYKVLVLN A274 713 AGVRLTVLATATPPG A41 243 GPPWGVRATRKTSER A119 400 INTNGSWINRTALN A197 557 AAYAAQGYKVLVLNP A275 714 GVRLTVLATATPPGS A42 244 PRLGVRATRKTSERS A120 401 NTNGSWHINRTALNC A198 558 AYAAQGYKVLVLNPS A276 715 VRLTVLATATPPGSV A43 245 RLGVRATRKTSERSQ A121 402 TNGSWHINRTALNCN A199 559 YAAQGYKVLVLNPSV B5 716 SGMFDSSVLCECYDA A44 246 LGVRATRKTSERSQP A122 403 NGSWHINRTALNCND A200 560 AAQGYKVLVLNPSVA B6 717 GMFDSSVLCECYDAG A45 247 GVRATRKTSERSQPR A123 404 GSWHINRTALNCNDS A201 561 AQGYKVLVLNPSVAA B7 718 MFDSSVLCECYDAGC A46 248 VRATRKTSERSQPRG A124 405 SWHINRTALNCNDSL A202 562 QGYKVLVLNPSVAAT B8 719 FDSSVLCECDAGCA A47 249 RATRKTSERSQPRGR A125 406 IQLVNTNGSWHINRT A203 563 GYKVLVLNPSVAATL B9 720 DSSVLCECYDAGCAW A48 250 ATRKTSERSQPRGRR A126 407 QLVNTNGSWHINRTA A204 564 YKVLVLNPSVAATLG B10 721 SSVLCECYDAGCAWY A49 251 TRKTSERSQPRGRRQ A127 408 LVNTNGSWHINRTAL A205 565 KVLVLNPSVAATLGF B11 722 SVLCECYDAGCAWYE A50 252 RKTSERSQPRGRRQP A128 409 VNTNGSWHINRTALN A206 566 VLVLNPSVAATLGFG B12 723 VLCECYDAGCAWYEL A51 253 KTSERSQPRGRRQPI A129 410 VDYPYRLWHYPCTVN A207 567 LVLNPSVAATLGFGA B13 724 LCECYDAGCAWYELT A52 254 TSERSQPRGRRQPIP A130 411 DYPYRLWHYPCTVNF A208 568 VLNPSVAATLGFGAY B14 725 CECYDAGCAWYELTP A53 255 SERSQPRGRRQPIPK A131 412 YPYRLWHYPCTVNFT A209 569 YLHAPTGSGKSTKVP B15 726 ECYDAGCAWYELTA A54 256 DPRRRSRNLGKVIDT A132 413 PYRLWHYPCTVNFTI A210 570 LHAPTGSGKSTKVPV B16 727 CYDAGCAWYELTPAE A55 257 PRRRSRNLGKVIDTL A133 414 YRLWHYPCTVNFTIF A211 571 HAPTGSGKSTKVPVA B17 728 YDAGCAWYELTPAET A56 258 RRRSRNLGKVIDTLT A134 415 RLWHYPCTVNFTIFK A212 572 APTGSGKSTKVPVAY B18 729 DAGCAWYELTPAETT A57 259 RRSRNLGKVIDTLTC A135 416 LWHYPCTVNFTIFKV A213 573 PTGSGKSTKVPVAYA B19 730 AGCAWYELTPAETTV A58 260 RSRNLGKVIDTLTCG A136 417 WHYPCTVNFTIFKVR A214 574 TGSGKSTKVPVAYAA B20 731 CCAWYELTPAETTVR A59 261 SRNLGKVIDTLTCGF A137 418 HYPCTVNFTIFKVRM A215 575 GSGKSTKVPVAYAAQ B21 732 CAWYELTPAETTVRL A60 262 RNLGKVIDTLTCGFA A138 419 YPCTVNFTIFKVRMY A216 576 SGKSTKVPVAYAAQG B22 733 AWYELTPAETTVRLR A61 263 NLGKVIDTLTCGFAD A139 420 PCTVNFTIFKVRMYV A217 577 GKSTKVPVAYAAQGY B23 734 WYELTPAETTVRLRA A62 264 LGKVIDTLTCGFADL A140 421 CTVNFTIFKVRMYVG A218 578 KSTKVPVAYAAQGYK B24 735 YELTPAETTVRLRAY A63 265 GKVIDTLTCGFADLM A141 422 TVNFTIFKVRMYVGG A219 579 STKVPVAYAAQGTKV B25 736 DAGCAWYELTPAETS A64 266 KVIDTLTCGFADLMG A142 423 VNFTIFKVRMYVGGV A220 580 TKVPVAYAAQGYKVL B26 737 AGCAWYELTPAETSV A65 267 VIDTLTCGFADLMGY A143 424 NFTIFKVRMYVGGVE A221 581 KVPVAYAAQGYKVLV B27 738 GCAWYELTPAETSVR A66 268 IDTLTCGFADLMGYI A144 425 FTIFKVRMYVGGVEH A222 582 VPVAYAAQGYKVLVL B28 739 CAWYELTPAETSVRL A67 269 DTLTCGFADLMGYIP A145 426 TIFKVRMYVGGVEHR A223 583 PVAYAAQGYKVLVLN B29 740 AWYELTPAETSVRLR A68 270 TLTCCFADLMGYIPL A146 427 IFKVRMYVGGVEHRL A224 584 VAYAAQGYKVLVLNP B30 741 WYELTPAETSVRLRA A69 271 LTCGFADLMGYIPLV A147 428 DYPYRLWHYPCTVNY A225 585 ITSTYGKFLADGGC B31 742 GMFDSVVLCECYDAG A70 272 TCGFADLMGYIPLVG A148 429 YPYRLWHYPCTVNYT A226 586 TYSTYGKFLADGGCS B32 743 SGMFDSVVLCECYDA A71 273 CGFADLMGYIPLVGA A149 430 PYRLWHYPCTVNYTI A227 587 YSTYGKFLADGCCSG B33 744 GMFDSVVLCECYDAG A72 274 GFADLMGYIPLVGAP A150 431 YRLWHYPCTVNYTIF A228 588 STYGKFLADGGCSGG B34 745 MFDSVVLCECYDAGA A73 275 FADLMGYIPLVGAPL A151 432 RLWHYPCTVNYTIFK A229 589 TYGKFLADGGCSGGA B35 746 FDSVVLCECYDAGAA A74 276 ADLMGYIPLVGAPLG A152 433 LWHYPCTVNYTIFKI A230 590 YGKFLADGGCSGGAY B36 747 DSVVLCECYDAGAAW A75 277 DLMGYIPLVGAPLGG A153 434 WHYPCTVNYTIFKIR A231 591 GKFLADGGCSGGAYD B37 748 SVVLCECYDAGAAWY A76 278 DPRHRSRNVGKVIDT A154 435 HYPCTVNYTIFKIRM A232 592 KFLADGGCSGGAYDI B38 749 VVLCECYDAGAAWYE A77 279 PRHRSRNVGKVIDTL A155 436 YPCTVNYTIFKIRMY A233 593 FLADGGCSGGAYDII B39 750 VLCECYDAGAAWYEL A78 280 RHRSRNVGKIDTLT A156 437 PCTVNYTIFKIRMYV A234 594 LADGGCSGGAYDIII B40 751 LCECYDAGAAWYELT B41 281 CECYDAGAAWYELTP B120 438 AGISGALVAFKIMSG C75 595 FPDLGVRVCEKMALY C154 752 DCTMLVNGDDLWIC B42 282 ECYDAGAAWYELTPA B121 439 GISGALVAFKIMSGE C76 596 PDLGVRVCEKMALYD C155 753 DPTMLVCGDDLVVIC B43 283 CYDAGAAWYELTPAE B122 440 VNLLPAILSPGALVV C77 597 DLGVRVCEKMALYDV C156 754 DPTMLVNGDDLWIC B44 284 YDAGAAWYELTPAET B123 441 NLLPAILSPGALWG C78 598 KGGKKAARLIVYPDL C157 755 LWARMILMTHFFSIL B45 285 DAGAAWYELTPAETT B124 442 LLPAILSPGALVVGV C79 599 GGKKAARLIVYPDLG C158 756 LWVRMVLMTHFFSIL B46 286 AGAAWYELTPAETTV C1 443 LPAILSPGALVVGVV C80 600 GKKAARLIVYPDLGV C159 757 DLPQIIERLHGLSAF B47 287 GAAWYELTIPAETTV C2 444 PAILSPGALVVGVVC C81 601 KKAARLIVYPDLGVR C160 758 DLPQIIQRLHGLSAF B48 288 AAWYELTPAETTVRL C3 445 AILSPGALVVGVVCA C82 602 KAARLIVYPDLGVRV C161 759 AVRTKLKLTPIPAAS B49 289 DAGAAWYELTPAETS C4 446 ILSPGALVVGVVCAA C83 603 AARLIVYPDLGVRVC C162 760 AVRTKLKLTPLPAAS B50 290 AGAAWYELTPAETSV C5 447 LSPGALVVGVVCAAI C84 604 ARLIVYPDLGVRVCE C163 761 SGGDIYHSLSRARPR B51 291 GAAWYELTPAETSVR C6 448 SPGALVVGVVCAAIL C85 605 RLIVYPDLGVRVCEK C164 762 SGGDIYHSVSRARPR B52 292 AAWYELTPAETSVRL C7 449 PGALVVGVVCAAILR C86 606 LIVYPDLGVRVCEKM C165 763 WGENETDVLLLNNTR B53 293 FWAKHMWNFISGIQY C8 450 GALVVGVV0AAILRR C87 607 IVPDLGVRVCEKMA C166 764 GENETDVLLLNNTRP B54 294 WAKHMWNFISGIQYL C9 451 ALVVGVVCAAILRRH C88 608 VYPDLGVRVCEKMAL C167 765 WFGCTWMNSTGFTKT B55 295 AKHMWNFISGIQYLA C10 452 LVVGWCAAILRRHV C89 609 YPDLGVRVCEKMALY C168 766 FGCTWMNSTGFTKTC B56 296 KHMWNFISGIQYLAG C11 453 VVGVVCAAILRRHVG C90 610 AQPGYPWPLYGNEGL C169 767 GCTWMNSTGFTKTCG B57 297 HMWNFISGIQYLAGL C12 454 VGVVCAAILRRHVGP C91 611 GQPGYPWPLYGNEGL C170 768 GLPVSARRGREILLG B58 298 MWNFISGIQYLAGLS C13 455 GVVCAAILRRHVGPG C92 612 AFCSAMYVGDLCGSV C171 769 LPVSARRGREILLGP B59 299 WNFISGIQYLAGLST C14 456 VVCAAILRRHVGPGE C93 613 AFCSALYVGDLCGSV C172 770 PVSARRGREILLGPA B60 300 NFISGIQYLAGLSTL C15 457 VCAAILRRHVGPGEG C94 614 ETVQDCNCSIYPGHV C173 771 VSARRGREILLGPAD B61 301 FISGIQYLAGLSTLP C16 458 CAAILRRHVGPGEGA C95 615 EFVQDCNCSIYPGHV C174 772 GLPVSALRGREILLG B62 302 ISGIQYLAGLSTLPG C17 459 AAILRRHVGPGEGAV C96 616 GVLAGLAYYSMVGNW C175 773 LPVSALRGREILLGP B63 303 SGIQYLAGLSTLPGN C18 460 AILRRHVGPGEGAVQ C97 617 GVLFGLAYFSMVGNW C176 774 PVSALRGREILLGPA B64 304 GIQYLAGLSTLPGNP C19 461 ILRRHVGPGEGAVQW C98 618 DQRPYCWHYAPRPCG C177 775 VSALRGREILLGPAD B65 305 IQYLAGLSTLPGNPA C20 462 LRRHVGPGEGAVQWM C99 619 DQRPYCWYPPRPCG C178 776 PDREVLYREFDEMEE B66 306 QYLAGLSTLPGNPAI C21 463 RRHVGPGEGAVQWMN C100 620 TCPTDCFRKHPEATY C179 777 DREVLYREFDEMEEC B67 307 YLAGLSTLPGNPAIA C22 464 RHVGPGEGAVQWMNR C101 621 YTKCGSGPWLTPRCL C180 778 REVLYREFDEMEECA B68 308 LAGLSTLPGNPAIAS C23 465 HVGPGEGAVQWMNRL C102 622 LNAACNWTRGERCDL C181 779 EVLYREFDEMEECAS B69 309 AGLSTLPGNPAIASI C24 466 VGPGEGAVQWMNRLI C103 623 LNAACNFTRGERCDL C182 780 VLYREFDEMEECASH B70 310 GLSTLPGNPAIASLM C25 467 GPGEGAVQWMNRLIA C104 624 IAQAEAALENLVVLN C183 781 LYREFDEMEECASHL B71 311 LSTLPGNPAIASLMA C26 468 PGEGAVQWMNRLIAF C105 625 IAQAEAALEKLVVLH C184 782 YYLTRDPTTPLARAA B72 312 STLPGNPAIASLMAF C27 469 GEGAVQWMNRLIAFA C106 626 TRVPYFVRAQGLIRA C185 783 YLTRDPTTPLARAAW B73 313 QYLAGLSTLPGNPAV C28 470 EGAVQWMNRLIAFAS C107 627 TRVPYFVRAHGLIRA C186 784 LTRDPTTPLARAAWE B74 314 YLAGLSTLPGNPAVA C29 471 GAVQWMNRLIAFASR C108 628 HAGLRDLAVAVEPVV C187 785 TRDPTTPLARAAWET B75 315 LAGLSTLPGNPAVAS C30 472 AVQWMNRLIAFASRG C109 629 AAGLRDLAVAVEPIV C188 786 RDPTTPLARAAWETA B76 316 AGLSTLPGNPAVASM C31 473 VQWMNRLIAFASRNGN C110 630 ITWGADTAACGDIIL C189 787 DPTTPLARAAWETAR B77 317 GLSTLPGNPAVASMM C32 474 QWMNRLIAFASRGNH C111 631 ITWGAETAACGDIIL C190 788 PTTPLARAWETARH B78 318 LSTLPGNPAVASMMA C33 475 WMNRLIAFASRGNHV C112 632 GQGWRLLAPITAYSQ C191 789 YYLTRDPTTPLARAA B79 319 STLPGNPAVASMMAF C34 476 MNRLAFASRGNHVS C113 633 TAYSQQTRGLLGCII C192 790 YLTRDPTTPLARAAW B80 320 GAAVGSIGLGKVLVD C35 477 NRLIAFASRGNHVSP C114 634 TAYSQQTRGLLGCIV C193 791 LTRDPTTPLARAAWE B81 321 AAVGSIGLGKVLVDI C36 478 RLIAFASRGNHVSPT C115 635 GCIITSLTGRDKNQV C194 792 TRDPTTPLARAAWET B82 322 AVGSIGLGKVLDIL C37 479 LIAFASRGNHVSPTH C116 636 GCIVVSMTGRDKTQV C195 793 RDPTTPLARAAWETV B83 323 VGSIGLGKVLVDILA C38 480 IAFASRGNHVSPTHY C117 637 VNGVCWTVYHGAGSK C196 794 DPTTPLARAAWETVR B84 324 GSIGLGKVLVDILAG C39 481 AFASRGNHVSPTHYV C118 638 KGPITQMYTNVDQDL C197 795 PTTPLARAAWETVRH B85 325 SIGLGKVLVDILAGY C40 482 VNLLPGILSPGALVV C119 639 KGPITQMYSSAEQDL B86 326 IGLGKVLVDILAGYG C41 483 NLLPGILSPGALVVG C120 640 GDSRGSLLSPRPVSY B87 327 GLGKVLVDILAGYGA C42 484 LLPGILSPGALVVGV C121 641 GDSRGALLSPRPVSY B88 328 LGKVLVDILAGYGAG C43 485 LPGILSPGALVVGVI C122 642 SYLKGSSGGPLLCPS B89 329 GKVLVDILAGYGAGV C44 486 PGILSPGALVVGVIC C123 643 SYLKGSSGGPVLCPS B90 330 KVLVDILAGYGAGVA C45 487 GILSPGALVVGVICA C124 644 GHAVGIFRAAVCTRG B91 331 VLVDILAGYGAGVAG C46 488 ILSPGALVVGVICAA C125 645 GVDPNIRTGVRTITT B92 332 LVDILAGYGAGVAGA C47 489 LSPGALVVGVICAAI C126 646 VPHPNIEEVALSNTG B93 333 VDILAGYGAGVAGAL C48 490 SPGALVVGVICAAIL C127 647 TGEIPFYGKAIPIEV B94 334 DILAGYGAGVAGALV C49 491 PGALVVGVICAAILR C128 648 TGEIPFYGKAIPLEV B95 335 ILAGYGAGVAGALVA C50 492 GALVVGVICAAILRR C129 649 PTSGDVVVVATDALM B96 336 LAGYGAGVAGALVAF C51 493 ALVVGVICAAILRRH C130 650 QTVDFSLDPTFTIET B97 337 AGYGAGVAGALVAFK C52 494 LVVGVICAAILRRHV C131 651 TLHGPTPLLYRLGAV B98 338 GYGAGVAGALVAFKI C53 495 VVGVI0AAILRRHVG C132 652 VQNEVTLTHPITKYI B99 339 YGAGVAGALVAFKIM C54 496 VGVIOAAILRRHVGP C133 653 LYREFDEMEECASHL B100 340 GAGVAGALVAFKIMS C55 497 GVICAAILRRHVGPG C134 654 TTLLFNILGGWVAAQ B101 341 AGVAGALVAFKIMSG C56 498 VICAAILRRHVGPGE C135 655 TTLLNILGGWLAAQ B102 342 GVAGALVAFKIMSGE C57 499 CAAILRRHVGPGEG C136 656 PSAASAFVGAGIAGA B103 343 GYGAGVAGALVAFKV C58 500 MNRLIAFASRGNHVA C137 657 PSAATGFVVSGLAGA B104 344 YGAGVAGALVAFKVM C59 501 NRLIAFASRGNHVAP C138 658 TPCSGSWLRDVWDWI B105 345 GAGVAGALVAFKVMS C60 502 RLIAFASRGNHVAPT C139 659 VAAEEYVEVTRVGDF B106 346 AGVAGALVAFKVMSG C61 503 LIAFASRGNHVAPTH C140 660 VAAEEYAEVTRHGDF B107 347 GVAGALVAFKVMSGE C62 504 IAFASRGNHVAPTHY C141 661 FFTEVDGVRLHRYAP B108 348 GKVLVDILAGYGAGI C63 505 AFASRGNHVAPTHYV C142 662 FFTELDGVRLHRYAP B109 349 KVLVDILAGYGAGIS C64 506 KGGRKPARLIVFPDL C143 663 FFTWVDGVQIHRYAP B110 350 VLVDILAGYGAGISG C65 507 GGRKPARLIVFPDLG C144 664 FFTWLDGVQIHRYAP B111 351 LVDILAGYGAGISGA C66 508 GRKPARLIVFPDLGV C145 665 YLVGSQLPCEPEPDV B112 352 VDILAGYGAGISGAL C67 509 RKPARLIVFPDLGVR C146 666 YLVGSQLPCDPEPDV B113 353 DILAGYGAGISGALV C68 510 KPARLIVFPDLGVRV C147 667 LPTWARPDYNPPLLE B114 354 ILAGYGAGISGALVA C69 511 PARLIVFPDLGVRVC C148 668 ASLRQKKVTFDRLQV B115 355 LAGYGAGISGALVAF C70 512 ARLIVFPDLGVRVCE C149 669 ASLRAKKVTFDRLQV B116 356 AGYGAGISGALVAFK C71 513 RLIVFPDLGVRVCEK C150 670 HIRSVWKDLLEDTET B117 357 GYGAGISGALVAFKI C72 514 LIVFPDLGVRVCEKM C151 671 IDTTIMAKNEVFCVQ B118 358 YGAGISGALVAFKIM C73 515 IVFPDLGVRVCEKMA C152 672 VMGSSYGFQYSPGQR B119 359 GAGISGALVAFKIMS C74 516 VFPDLGVRVCEKMAL C153 673 DCTMLVCGDDLVVIC Peptide ID SEQ ID (Ipep) NO: 1506 796 MSTNPKPQRKTKRNTNRRPQDVKFPGGGQIVGGVYLLPRRGPRLGVRATRKTSERSQPRGRRQPIPK 1526 797 VNLLPAILSPGALVVGVVCAAILRRHVGPGEGAVQWMNRLIAFASRGNHVSPTHYV 1545 798 IKGGRHLTFCHSKKKCDELA 1546 799 TVPQDAVSRSQRRGRTGRGR 1547 800 YLVAYQATVCARAQAPPPSWD 1551 801 HLHAPTGSGKSTKVPAAYAAQGYKVLVLNPSVAATLGFGAY 1552 802 YLHAPTGSGKSTKVPVAYAAQGYKVLVLNPSVAATLGFGAY 1553 803 GAAVGSICLGKVLVDILAGYGAGVAGALVAFKIMSGE 1554 804 GAAVGSIGLGKVLVDILAGYGAGVAGALVAFKVMSGE 1555 805 GAAVGSIGLGKVLVDILAGYGAGISGALVAFKIMSGE 1556 806 FTEAMTRYSAPPGDPP 1557 807 SSMPPLEGEPGDPDL 1558 808 CGYRRCRASGVLTTS 1559 809 PVNSWLGNIIMYAPT 1560 810 PVNSWLGNIIQYAPT 1561 811 SGMFDSSVLCECYDAGCAWYELTPAETTVRLRAY 1562 812 SGMFDSSVLCECYDAGCAWYELTPAETSVRLRAY 1563 813 SGMFDSVVLCECYDAGAAWYELTPAETTVRLRAY 1564 814 SGMFDSVVLCECYDAGAAWYELTPAETSVRLRAY 1565 815 FWAKHMWNFISGIQYLAGLSTLPGNPAIASLMAF 1577 816 GEVQVVSTATQSFLAT 1578 817 GEVQVLSTVTQSFLGT 1579 818 FTDNSSPPAVPQTFQV 1580 819 FSDNSTPPAVPQTYQV 1581 820 NAVAYYRGLDVSVIPT 1587 821 VNLLPGILSPGALVVGVICAAILRRHVGPGEGAVQWMNRLIAFASRGNHVAPTHYV 1588 822 TTILGIGTVLDQAETAGARLVVLATATPPGSVT 1589 823 TSILGIGTVLDQAETAGARLVVLATATPPGSVT 1590 824 TSILGIGTVLDQAETAGVRLTVLATATPPGSVT 1591 825 TTILGIGTVLDQAETAGVRLTVLATATPPGSVT 1592 826 FWAKHMWNFISGIQYLAGLSTLPGNPAVASMMAF 1603 827 VFTGLTHIDAHFLSQTKQ 1604 828 VVCCSMSYTWTGALITPC 1605 829 VVCCSMSYSWTGALITPC 1606 830 VLTSMLTDPSHITAETA 1607 831 VLTSMLTDPSHITAEAA 1613 832 ASSSASQLSAPSLRATCTT 1614 833 LTPPHSARSKFGYGAKDVR 1615 834 LTPPHSADSKFGYGAKDVR 1616 835 LTPPHSAKSKYGYGAKEVR 1617 836 LTPPHSARSKYGYGAKEVR 1618 837 PMGFSYDTRCFDSTVTE 1619 838 PMGFAYDTRCFDSTVTE 1620 839 TGDFDSVIDCNTCVTQ 1621 840 TGDFDSVIDCNVAVTQ 1622 841 NTPGLPVCQDHLEFWE 1623 842 YLVAYQATVCARAXAPPPSWD 1624 843 LEDRDRSELSPLLLSTTEW 1625 844 LEDRDRSQLSPLLHSTTEW 1626 845 ASSSASQLSAPSLKATCTT 1627 846 PEYDLELITSCSSNVSVA 1628 847 VCGPVYCFTPSPVVVGTTDR 1629 848 GWAGWLLSPRGSRPSWGP 1630 849 LLFLLLADARVCACLWM 1631 850 SGHRMAWDMMMNWSPT 1632 851 TGHRMAWDMMMNWSPT 1641 852 ITYSTYGKFLADGGCSGGAYDIIICDECHS 1647 853 ARALAHGVRVLEDGVNYATGNLPGCSFSIFLLALLSC 1648 854 DPRRRSRNLGKVIDTLTCGFADLMGYIPLVGAPLGG 1649 855 DPRHRSRNVGKVIDTLTCGFADLMGYIPVVGAPLGG 1650 856 VDYPYRLWHYPCTVNFTIFKVRMYVGGVEHRL 1651 857 VDYPYRLWHYPCTVNYTIFKIRMYVGGVEHRL 1652 858 XGGRKPARLIVFPDLGVRVCEKMALYDV 1653 859 KGGKKAARLIVYPDLGVRVCEKMALYDV 1654 860 IQLINTNGSWHINRTALNCNDSL 1655 861 IQLVNTNGSWHINRTALNCNDSL 1656 862 LPALSTGLIHLHQNIVDVQYLYG

For epitope capture, each peptide pool was incubated with soluble recombinant HLA-class II molecules and specific binding was assessed by an SDS-stability assay. The results using the HLA molecules DRB1*0401, DRB1*0404 and DRB1*0101 are shown in FIGS. 2 and 3 respectively: 28 peptide pools were found which bind to DRB1*0401 molecules: no. 1, 2, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20 from “row” pools and no. 23, 25, 26, 27, 29, 30, 31, 34, 36, 38, 39 and 40 from “column” pools (FIG. 2). 35 peptide pools out of 40 tested were positive in binding to DRB1*0404 molecules (FIG. 3), while all peptide pools showed binding activity to DRB1*0101 molecules. By finding the intersections of reactive pools in the array, potential individual binders were determined and re-checked for binding affinity individually.

All individually confirmed peptides are summarized in Table 2. Binding to DRB1*0401 is shown in FIG. 4: 54 individual peptides were identified as ligands of this HLA-type. Often several overlapping 15mers in a row bound to HLA allowing identification of their core binding regions. Peptide differing only by one or two amino acids representing variants (see Table 1) usually bound both to soluble HLA class II molecules. Such “duplicates” were considered to represent the same epitope. Thus, 31 ligands capable to bind to DRB1*0401 were identified, including 11 previously known class II epitopes. From the latter, however, only two (A202-A206 and B60-B68) had been known to be restricted to DR4 (see Table 2). 20 ligands are candidates for novel epitopes. For DRB1*0404, 64 binders designated as 28 potential epitopes were determined, 4 of them belong to already known epitopes (FIG. 5, Table 2). For DRB1*0101, 83 peptides representing 44 potential epitopes were identified (FIG. 6, Table 2). Of those, 7 had been described previously but with different HLA restriction.

All individually confirmed peptides binding to at least one of the 3 above mentioned HLA types were also tested for affinity to DRB1*0701 molecules in a peptide-competition assay (FIG. 7, Table 2). Here, 50 ligands were identified. Of those, 7 correspond to already known class II epitopes, but only one was described as DRB1*0701 epitope (A202-A206). TABLE 2 HCV derived peptides binding to soluble HLA class II molecules. About 400 15- to 23-mer peptides derived from conserved regions of HCV were analyzed by the Epitope Capture Method using pools of up to 20 peptides arrayed in matrix format (see FIG. 1) and four different HLA class II molecules. Specific binding was confirmed for individual peptides. Known/new SEQ potential ID Binding to DRB1 epitope, HLA ID NO: Peptide Sequences *0101 *0401 *0404 *0701 coverage A120 863 NTNGSWHINRTALNC * nb A122 864 NGSWHINRTALNCND * * * new DRB1*0101, A124 865 SWHINRTALNCNDSL * *0404, *0701: 45- 55% B25 866 DAGCAWYELTPAETS *** * *** B26 867 AGCAWYELTPAETSV *** *** *** nb new DRB1*0101, B28 868 CAWYELTPAETSVRL *** ** *** * *0404, *0701: 45- B30 869 WYELTPAETSVRLRA ** * ** nb 55% B46 870 AGAAWYELTPAETTV *** *** nb new DRB1*0101, B48 871 AAWYELTPAETTVRL *** *** ** *0404, *0701: 45- 55% B84 872 GSIGLGKVLVDILAG * * * B86 873 IGLGKVLVDILAGYA * ** * ** new DRB1*0101, B88 874 LGKVLVDILAGYGAG * ** * *0404, *0701: 45- B92 875 LVDILAGYGAGVAGA * nb 55% C106 876 TRVPYFVRAQGLIRA * * * * new DRB1*0101, *0404, *0701: 45- 55% C113 877 TAYSQQTRGLLGCII *** * new DRB1*0101, C114 878 TAYSQQTRGLLGCIV *** * * * *0404, *0701: 45- 55% 1627 879 PEYDELELITSCSSNVSVA *** *** ** new DRB1*0101, *0404, *0701: 45- 55% 1628 880 VCGPVYCFTPSPVVVGTTDR *** ** * * new DRB1*0101, *0404, *0701: 45- 55% 1629 881 GWAGWLLSPRGSPRPSWGP * * ** * new DRB1*0101, *0404, *0701: 45- 55% 1604 882 VVCCSMSYTWTGALITPC * ** *** new DRB1*0101, *0404, *0701: 45- 55% 1630 883 LLFLLLADARVCACLWM * nb *** new DRB1*0101, *0701: 40-50% C97 884 GVLFGLAYFSMVGNW ** ** nb ** new DRB1*0101, *0701: 40-50% 1547 885 YLVAYQATVCARAQAPPPSWD *** NB ** new DRB1*0101, *0701: 40-50% B94 886 DILAGYGAGVAGALV * nb nb nb B95 887 ILAGYGAGVAGALVA * nb nb new DRB1*0101, B96 888 LAGYCAGVAGALVAF ** ** nb * *0404, *0701: 40- B97 889 AGYGAGVAGALVAFK * nb nb 50% B98 890 GYGAGVACALVAKFI * nb nb nb A272 891 ETAGVRLTVLATATT * * nb A274 892 AGVRLTVLATATPPG * nb nb new DRB1*0101, A276 893 VRLTVLATATPPGSV nb * *0404, *0701: 40- 50% B120 894 AGISGALVAFKIMSG * nb * *** new DRB1*0101, *0404, *0701: ˜45 B122 895 VNLLPAILSPGALVV * nb * * new DRB1*0101, *0404, *0701: ˜45 C108 896 HAGLRDLAVAVEPVV * nb * * new DRB1*0101, *0404, *0701: ˜45 C134 897 TTLLFNILGGWVAAQ * nb * ** new DRB1*0101, *0404, *0701: ˜45 C152 898 VMGSSYGFQYSPGQR * nb * * new DRB1*0101, *0404, *0701: ˜45 1606 899 VLTSMLTDPSHITAETA nb *** ** ** new DRB1*0401, *0404, *0701: ˜45 1607 900 VLTSMLTDPSHITAEAA nb *** ** * new DRB1*0401, *0404, *0701: ˜45 1577 901 GEVQVVSTATQSFLAT nb * *** *** new DRB1*0401, *0404, *0701: ˜45 1578 902 GEVQVLSTVTQSFLGT nb * *** *** new DRB1*0401, *0404, *0701: ˜45 B50 903 AGAAWYELTPAETSV *** *** *** new DRB1*0101, B52 904 AAWYELTPAETSVRL *** *** *** nb *0401, *0404: ˜40 1623 905 YLVAYQATVCARAKAPPPSWD * ** new DRB1*0101, *0401, *0404: ˜40 C130 906 QTVDFSLDPTFTIET ** *** ** nb new DRB1*0101, *0401, *0404: ˜40 1603 907 VFTGLTHIDAHFLSQTKQ *** nb nb * new DRB1*0101, *0701: ˜40 C96 908 GVLAGLAYYSMVGNW ** nb nb * new DRB1*0101, *0701: ˜40 C191 909 YYLTRDPTTPLARAA nb *** nb new DRB1*0401, *0701: ˜40 A216 910 SGKSTKVPVAYAAQG nb * nb nb A218 911 KSTKVPVAYAAQGYK nb * nb new DRB1*0101, A220 912 TKVPVAYAAQGYKVL * ** nb *0401 ˜35 A222 913 VPVAYAAQGYKVLVL * nb nb nb A224 914 VAYAAQGYKVLVLNP * nb nb A242 915 TILGIGTVLDQAETA nb nb * new DRB1*0101, A244 916 LGIGTVLDQAETAGA * * nb nb *0401: ˜35 C92 917 AFCSAMYVGDLCGSV * ** nb nb new DRB1*0101, C93 918 AFCSALYVGDLCGSV * * nb *0401: ˜35 A174 919 PALSTGLLHLHQNIV nb * * new DRB1*0404, *0701: ˜25-30 B32 920 SGMFDSVVLCECYDA * nb *** B34 921 MFDSVVLCECYDAGA * nb *** nb new DRB1*0101, B36 922 DSVVLCECYDAGAAW * nb *** *0404: ˜20-25 B38 923 VVLCECYDAGAAWYE nb nb * nb B100 924 GAGVAGALVAFKIMS ** nb ** new DRB1*0101, B102 925 GVAGALVAFKIMSGE *** nb *** *0404: ˜20-25 C135 926 TTLLLNILGGWLAAQ ** nb * new DRB1*0101, *0404: ˜20-25 C162 927 AVRTKLKLTPLPAAS nb * * nb new DRB1*0401, *0404: ˜20-25 1618 928 PMGFSYDTRCFDSTVTE nb nb ** new DRB1*0701: ˜25 1622 929 NTPGLPVCQDHLEFWE nb nb *** new DRB1*0701: ˜25 1624 930 LEDRDRSELSPLLLSTTEW nb nb * new DRB1*0701: ˜25 1546 931 TVPQDAVSRSQRRGRTGRGR nb nb nb * new DRB1*0701: ˜25 1556 932 FTEAMTRYSAPPGDPP nb nb nb * new DRB1*0701: ˜25 A114 933 LPGCSFSIFLLALLS ** nb nb nb new DRB1*0101: ˜20 B58 934 MWNFISGIQYLAGLS * nb nb new DRB1*0101: ˜20 B112 935 VDILAGYGAGISGAL * B114 936 ILAGYGAGISGALVA *** new DRB1*0101: ˜20 B116 937 AGYGAGISGALVAFK *** nb nb B118 938 YGAGISGALVAFKIM *** nb B18 939 DAGCAWYELTPAETT *** nb nb B20 940 GCAWYELTPAETTVR *** nb new DRB1*0101: ˜20 B22 941 AWYELTPAETTVRLR ** nb nb C112 942 GQGWRLLAPITAYSQ ** nb new DRB1*0101: ˜20 C116 943 GCIVVSMTGRDKTQV * nb nb new DRB1*0101: ˜20 C122 944 SYLKGSSGGPLLCPS * nb nb new DRB1*0101: ˜20 C127 945 TGEIPFYGKAIPIEV * nb new DRB1*0101: ˜20 C144 946 FFTWLDGVQIHRYAP ** nb nb new DRB1*0101: ˜20 C159 947 DLPQIIERLHGLSAF * nb nb nb new DRB1*0101: ˜20 C160 948 DLPQIIQRLHGLSAF * nb C174 949 GLPVSALRGREILLG * nb nb new DRB1*0101: ˜20 1558 950 CGYRRCRASGVLTTS *** nb nb new DRB1*0101: ˜20 1581 951 NAVAYYRGLDVSVIPT ** nb nb nb new DRB1*0101: ˜20 C95 952 EFVQDCNCSIYPGHV nb ** nb nb new DRB1*0401: ˜20 C129 953 PTSGDVVVVATDALM nb nb ** new DRB1*0404: ˜5 C157 954 LWARMILMTHFESIL nb nb * nb new DRB1*0404: ˜5 C158 955 LWVRMVLMTHFFSIL nb * A254 956 ETAGARLVVLATATP nb nb * A256 957 AGARLVVLATATPPG nb nb * new DRB1*0404: ˜5 A258 958 ARLVVLATATPPGSV nb nb ** 1605 959 VVCCSMSYSWTGALITPC nb nb * nb new DRB1*0404: ˜5 C109 960 AAGLRDLAVAVEPIV nb * new DRB1*0404: ˜5 C161 961 AVRTKLKLTPIPAAS nb * new DRB1*0404: ˜5 A60 962 LGKVIDTLTCGFA ** nb nb ** known DR4, DR8, DR15 A61 963 GKVIDTLTCGFAD ** new DR*0101, 0701 A70 964 TCGFADLMGYIPLVG * nb nb A72 965 GFADLMGYIPLVGAP *** * ** known class II A74 966 DLMGYIPVVGAPLGG *** *** ** DR*0101, 0404, 0701 A88 967 CGFADLMGYIPVVGA ** ** * A90 968 FADLMGYIPVVGAPL *** *** known class II A92 969 DLMGYIPVVGAPLGG *** *** *** DR*0101, 0404, 0701 A96 970 LAHGVRVLEDGVNYA nb *** nb A98 971 HGVRVLEDGVNYATG nb *** *** ** known DR11 A100 972 VRVLEDGVNYATGNL nb *** *** * new DR*0401, A102 973 VLEDGVNYATGNLPG nb * 0404, 0701 A104 974 EDGVNYATGNLPGCS nb * nb nb A200 975 AAQGYKVLVLNPSVA nb *** ** A202 976 QGYKVLVLNPSVAAT *** *** *** *** known DRB1*0401, A204 977 YKVLVLNPSVAATLG *** ** *** *** 0701, DR11, DR15 A206 978 VLVLNPSVAATLGFG *** *** *** *** new DR*0101 C30 979 AVQWMNRLIAFASRG * nb known DR11, DQ5, also DR*0101 B60 980 NFISGIQYLAGLSTL ** nb 8 B62 981 ISGIQYLAGLSTLPG *** *** ** B64 982 GIQYLAGLSTLPGNP *** *** ** know DR#0401, B66 983 QYLAGLSTLPGNPAI * *** ** 1101 B68 984 LAGLSTLPGNPAIAS * *** ** new 0101, 0404, 0701 C124 985 GHAVGIFRAAVCTRG ** * nb ** known DR*0101, 0401, 0701 1620 986 TGDFDSVIDCNTCVTQ nb nb * new DR*0404 1621 987 TGDFDSVIDCNVAVTQ * nb nb known DR13, llso DR*0101, 0401 1631 988 SGHRMAWDMMMNWSPT nb nb known class II, also DR*0401 1632 989 TGHRMAWDMMMNWSPT nb * known class II, also DR*0401 *** strong binding ** intermediate binding * weak binding nb no binding Boldface peptide IDs indicates HLA-ligands with confirmed immunogenicity in HLA-transgenic mice Boldface peptide sequences indicate putative core binding regions based on prediction algorithms as described in the test. ¹⁾immunogenic in DRB1 *0401 transgenic mice.

Some of the highly promiscuous peptides and/or with computer algorithm (SYFPEITHI (SEQ ID NO:203), TEPITOPE (SEQ ID NO:204))-predicted affinities were checked for binding to soluble HLA-DRB1*1101 molecules in a peptide-competition assay as it is described for HLA-DRB1*0701. Several known DR11 epitopes were used as controls and were confirmed to bind HLA-DRB1*1101 molecules in vitro. Among newly identified HLA-DRB1*1101 binders, there are peptides with IDs A120, A122, A141, C114, C134, 1426, 1628, 1629 of high affinity, 5 peptides with IDs C106, C135, 1578, 1547, 1604 of moderate affinity and 4 peptides with IDs B46, B48, B86, B96 of weak affinity ligands.

In summary eight novel ligands binding at least to HLA-DRB1*0101, *0401, *0404, *0701 and *1101 (Tab. 2: peptide Ids A120, A122, A141, 1604, 1547, 1628, 1629, and Tab. 6: peptide ID 1426); novel 10 ligands binding at least to HLA-DRB1*0101, *0401, *0404 and *0701 (Tab. 2: peptide IDs A120-A124, B25-B30, B46-B48, B84-B92, C106, C113-C114, 1627, 1628, 1629, 1604); 5 novel ligands binding at least to HLA-DRB1*0101, *0401 and *0701, 5 novel ligands binding at least to HLA-DRB1*0101, *0404 and *0701, 4 novel ligands binding at least to HLA-DRB1*0401, *0404 and *0701, 3 novel ligands binding at least to HLA-DRB1*0101, *0401 and *0404, 2 novel ligands binding at least to HLA-DRB1*0101 and *07.01, 1 novel ligand binding at least to HLA-DRB1*0401 and *0701, 3 novel ligands binding at least to HLA-DRB1*0101, *0401, 1 novel ligand binding at least to HLA-DRB1*0404 and *0701, 4 novel ligand binding at least to HLA-DRB1*0101 and *0404, 5 novel ligands binding at least to HLA-DRB1*0701, 13 novel ligands binding at least to HLA-DRB1*0101, 1 novel ligand binding at least to HLA-DRB1*0401, and 6 novel ligands binding at least to HLA-DRB1*0404.

Moreover, 12 known HLA class II epitopes were confirmed, in several cases binding to alleles not reported yet was demonstrated (Tab. 2, last group).

Having established physical binding too HLA class II it is straightforward to verify immunogenicity for a given ligand: for instance peptide IDs A120-A124, B46-B48, 1627, 1604, 1630, 1547, 1623, B112-118, 1558, all binding to one or more HLA class II alleles were also shown to be immunogenic in HLA-DRB1*0401 transgenic mice (see Example II).

To determine the optimal epitope within a longer polypeptide, mice can be vaccinated with a longer polypeptide incorporating the candidate epitope sequences. Generation of specific CD4+ T cell responses against naturally processed and presented epitopes can then be assayed by re-stimulation of murine splenocytes or lymph node cells with overlapping 15-mers and IFN-gamma ELIspot. Final confirmation/validation of the newly identified HLA-ligands can be achieved by testing these peptides with T-cells from humans. Ideally, these comprise therapy responders or subjects spontaneously recovered from infection.

Example II Immunogenicity of HCV-Derived Peptides in HLA-Transgenic Mice

Synthetic HCV-derived peptides (from conserved regions) were investigated for immunogenicity in HLA-transgenic mice: 36 of 68 peptides tested were found to induce peptide-specific IFN-gamma-producing cells in vaccination experiments. As summarized in Table 3, some peptides were either immunogenic (+, less than 100 peptide-specific cells among a million splenocytes) or even strongly immunogenic (++, more than 100 peptide-specific cells among a million splenocytes) in DR4- and/or A*0201-transgenic mice. TABLE 3 SEQ ID Ipep DRB1*0401 A*0201 B*0702 NO Sequence 1506 + 990 MSTNPKPQRKTKRNTNRRPQDVKFPGGGQIVGGVYLLPRRGFRLGVRATRKTSERSQ PRGRRQPIPK 1526 + + + 991 VNLLPAILSPGALVVGVVCAAILRRHVGPGEGAVQWMNRLIAFASRGNHVSPTHYV 1545 + 992 IKGGRHLIFCHSKKKCDELA 1547 ++ +++ 993 YLVAYQATVCARAQAPPPSWD 1552 + + 994 YLHAPTGSGKSTKVPVAYAAQGYKVLVLNPSVAATLGFGAY 1553 + + 995 GAAVGSIGLGKVLVDILAGYGAGVAGALVAFKIMSGE 1555 + + + 996 GAAVGSIGLGKVLVDILAGYGAGISGALVAFKIMSGE 1558 ++ + ++ 997 CGYRRCRASGVLTTS 1559 + ++ 998 PVNSWLGNIIMYAPT 1560 + ++ 999 PVNSWLGNIIQYAPT 1562 + 1000 SGMFDSSVLCECYDAGCAWYELTPAETSVRLRAY 1563 + + 1001 SGMFDSVVLCECYDAGAAWYELTPAETTVRLRAY 1565 ++ ++ + 1002 FWAKHMWNFISGIQYLAGLSTLPGNPAIASLMAF 1577 + + 1003 GEVQVVSTATQSFLAT 1578 + 1004 GEVQVLSTVTQSFLGT 1580 + 1005 FSDNSTPPAVPQTYQV 1587 + + 1006 VNLLPGILSPGALVVGVICAAILRRHVGPGEGAVQWMNRLIAFASRGNHVAPTHYV 1592 ++ ++ + 1007 FWAKHMWNFISGIQYLAGLSTLPGNPAVASMMAF 1604 ++ ++ ++ 1008 VVCCSMSYTWTGALITPC 1605 + + + 1009 VVCCSMSYSWTGALITPC 1615 + 1010 LTPPHSAKSKFGYGAKDVR 1616 + 1011 LTPPHSAKSKYGYGAKEVR 1617 + 1012 LTPPHSARSKYGYGAKEVR 1621 + + + 1013 TGDFDSVIDCNVAVTQ 1623 + + + 1014 YLVAYQATVCARAKAPPPSWD 1624 + 1015 LEDRDRSELSPLLLSTTEW 1625 + 1016 LEDRDRSQLSPLLHSTTEW 1627 + + ++ 1017 PEYDLELITSCSSNVSVA 1628 ++ 1018 VCGPVYCFTPSPVVVGTTDR 1630 ++ ++ 1019 LLFLLLADARVCACLWM 1631 + + 1020 SGHRMAWDMMMNWSPT 1632 + 1021 TGHRMAWDMMMNWSPT 1641 + 1022 ITYSTYGKFLADGGCSGGAYDIIICDECHS 1647 + + 1023 ARALAHGVRVLEDGVNYATGNLPGCSFSIFLLALLSC 1649 + 1024 DPRHRSRNVGKVIDTLTCGFADLMGYIPVVGAPLGG 1650 ++ ++ + 1025 VDYPYRLWHYPCTVNFTIFKVRMYVGGVEHRL 1651 ++ ++ + 1026 VDYPYRLWHYPCTVNYTIFKIRMYVGGVEHRL 1652 ++ + 1027 KGGRKPARLIVFPDLGVRVCEKMALYDV 1653 + 1028 KGGKKAARLIVYPDLGVRVCEKMALYDV 1654 ++ + 1029 IQLINTNGSWHINRTALNCNDSL 1655 ++ + 1030 IQLVNTNGSWHINRTALNCNDSL 1656 + 1031 LPALSTGLIHLHQNIVDYQYLYG

Peptide 1526, 1565, 1631, also shown to be immunogenic in HLA-DRB1*0401 transgenic mice contain known class II epitopes. Peptide IDs 1526, 1553, 1565, 1587, 1623, 1630 also shown to be immunogenic in HLA-A*0201 transgenic mice contain known A2 epitopes.

For further characterizing the novel epitopes provided herewith, one may define the exact HLA restriction of these epitopes and the minimal epitopes within the sequences recognized by T cells. Both can be done by a variety of well-established approaches known to the one skilled in the art (Current Protocols in Immunology, John Wiley & Sons, Inc.).

First, publicly available programs can be used to predict T cell epitopes on the basis of binding motifs. These include for instance: http://bimas.dcrt.nih.gov/molbio/hla_bind/(Parker et al. 1994), http://134.2.96.221/scripts/MHCServer.dll/home.htm (Rammensee at al. 1999), http://mypage.ihost.com/usinet.hamme76/(Sturniolo et al. 1999). The latter prediction algorithm offers the possibility to identify promiscuous T helper-epitopes, i.e. peptides that bind to several HLA class II molecules. These predictions can be verified by testing of binding of the peptide to the respective HLA.

A way of quickly discerning whether the response towards a peptide is class I or class II restricted is to repeat the ELIspot assay with pure CD4+ or CD8+ T cell effector populations. This can for instance be achieved by isolation of the respective subset by means of magnetic cell sorting. Pure CD8+ T cells can also be tested in ELIspot assays together with artificial antigen-presenting-cells, expressing only one HLA molecule of interest. One example are HLA-A*0201 positive T2 cells (174CEM.T2, Nijman et al., 1993). Alternatively, one can use ELIspot assays with whole PBMCs in the presence of monoclonal antibodies specifically blocking either the CD4+ or CD8+ T cell sub-population. Exact HLA restriction can be determined in a similar way, using blocking monoclonal antibodies specific for a certain allele. For example the response against an HLA-A24 restricted epitope can be specifically blocked by addition of an HLA-A24 specific monoclonal antibody.

For definition of the minimal epitopes within the peptide sequences recognized by T cells, one can test overlapping and truncated peptides (e.g. 8-, 9-, 10-mers) with splenocytes from immunized transgenic mice or T-cells from humans recognizing the respective epitope.

Example III HLA Restriction of Immunogenic HCV-Derived Peptides Investigated in Transgenic Mice

Groups of 5 mice (HLA-A*0201-, HLA-DRB1*0401- and HLA-B*0702 transgenic mice, male, 8-14 weeks of age) were injected subcutaneous into the hind footpads with 100 μg of peptide +IC31 per mouse (50 μg per footpad). (PCT/EP01/12041, WO 02/32451 A1 and PCT/EP01/06433, WO 01/93905 A1; IC31 is a combination of the immunizer disclosed in WO 01/93905 and WO 02/32451).

6 days after vaccination single cell suspension of pooled spleens were prepared and additionally pure fractions of CD8+ in the case of A2 and B7 tg mice (CD8+ fraction for B7 mice containing 97% of CD8 and 1.5% of CD4 cells and for A2 tg mice 83% of CD8 and 8% of CD4 cells) and CD4+ for DR4tg mice (CD4+ fraction for DR4tg mice containing 98% of CD4 cells and 0.2% of CD8 cells) were separated from the spleen cell suspension using MACS separating kit (Miltenyi, Germany). All cells (not separated cells, positive and corresponding negative fractions) were re-stimulated ex vivo with relevant peptide (for instance Ipep1604) and irrelevant peptides as negative control (known HLA-DRB1*0401 CMV-derived epitope Ipep 1505, HLA-B*0702 HIV-derived epitope Ipep 1787, or HLA-A*0201 tyrosinase-derived epitope Ipep1124) to detect INF-γ producing cells in ELISpot assay.

As an example shown in FIG. 8-10 the Ipep1604 (VVCCSMSYTWTGALITPC (SEQ ID NO:30), in combination with immunizer IC31) was able to induce high numbers of specific INF-γ producing T cells in all three transgenic class I and II mouse strains. This was shown not only with whole spleen derived cells but also with enriched fractions of CD8+ cells correspondingly for A2 and B7 and CD4+ cells for DR4tg mice. Similar, albeit weaker responses were seen with Ipep1605 (VVCCSMSYSWTGALITPC (SEQ ID NO:126)), a sequence variant with a serine instead of a threonine.

Thus, Ipep1604 contains class I epitopes for HLA-A*0201 and HLA-B*0702 and a class II epitope for HLA-DRB1*0401 molecules.

As shown in Tables 2 and 6, Ipep 1604 binds to class II molecules in a promiscuous manner. Thus, it contains further epitopes, at least for HLA-DRB1*0101, DRB1*0404, DRB1*0701 and DRB1*1101.

Other peptides were analysed in a similar way: Ipeps 1605, 1623, 1547, 1558, 1559, 1560, 1565, 1592, 1650, 1654 and 1655 were confirmed to contain human HLA-DRB1*0401 epitopes. Again, for most of these epitopes binding is not limited to HLA-DRB1*0401 as shown in Tables 2 and 6.

Ipeps 1565, 1605 and 1650 were confirmed to contain human HLA-A*0201 epitopes.

Ipeps 1506, 1587 were confirmed to contain human HLA-B*0702 epitopes.

Ipep 1843 with sequence LPRRGPRL (SEQ ID NO:1046) was shown to be the HLA-B*0702 minimal epitope contained in 1506:

FIG. 10 shows mouse IFN-gamma ELIspot with splenocytes or separated CD8+ or CD4+ cells from HLA-A*0702 transgenic mice vaccinated with Ipep1506+IC31 or Ipep1835+IC31.

FIG. 10 A) and B) shows that after a single vaccination with either Ipep 1506+IC31 or Ipep1835+IC31, upon restimulation with overlapping 15mers, the 15mers A30 to A37 (see Tab.1) react. The common sequence of these 15mers is LPRRGPRL (SEQ ID NO:1046) (Ipep 1843, see Tab.4).

FIG. 10 C) confirms these findings: after a single vaccination with either Ipep1506+IC31 or Ipep14835+IC31, significant interferon-gamma induction against Ipep14843 can be detected. In both cases Ipep 1790 an HIV NEF-derived HLA-B*0702 epitope (sequence RPMTYKAAL (SEQ ID NO:1032)) was used as negative control for restimulation.

Ipep 1838 with sequence SPGALVVGVI (SEQ ID NO:1045) (see Tab.4) was shown to be an HLA-B*0702 minimal epitope contained in 1587: In the case of Ipep14587 a different approach was taken: the sequence of Ipep14587 was inspected for HLA-B*0702 binding motifs and a couple of short peptides were synthesized accordingly. These were tested in a competition-type peptide binding assay using soluble HLA-B*0702 and the FITC-labelled reference peptide LPCVLWPVL (SEQ ID NO:1033), which is a known HLA-B*0702 epitope derived from EBV (Stuber et al., 1995). Peptide Ipep14838 showed ˜30% competition when used in 80-fold molar excess for 48 h at 37° C. Thus it is likely to present the minimal HLA-B*0702 epitope contained in Ipep 1587.

Example IV Identification and Confirmation of Novel HCV Peptides Reactive in IFN-Gamma ELIspot with Human PBMC from HCV Therapy Responders or Patients with Spontaneous Recovery

40 peptide mixtures in matrix format (FIG. 1) containing synthetic peptides derived from conserved regions of HCV (Table 1) were screened in IFN-gamma ELIspot using PBMC from more than 50 individuals who were either responders to interferon/ribavirin standard therapy, or, who had spontaneously cleared HCV (i.e. all subjects were HCV antibody positive, but HCV-RNA negative). PBMC from such individuals are supposed to contain the relevant T-cell populations responsible for clearing HCV. Thus, peptides discovered or confirmed by using these PBMC are likely to represent the structural determinants of immune protection against/clearance of HCV. Based on the results from this primary matrix-screen, a number of peptides were chosen for individual re-testing in IFN-gamma ELIspot using PBMC from selected donors. In addition, several new peptides incorporating sequences from overlapping reactive peptides or avoiding critical residues like cystein were synthesized. These are summarized in Table 4. TABLE 4 additional peptides derived from conserved regions of HCV. Peptide Peptide sequence SEQ ID ID (1 amino acid code) NO: 1006    MWNFISGIQYLAGLSTLPGN 1034 1334 HMWNFISGI 1035 1425           NFISGIQYLAGLSTLPGNPA 1036 1426 HMWNFISGIQYLAGLSTLPGNPA 1037 1798 IGLGKVLVDILAGYGAGVAGALVAFK 1038 1799 AAWYELTPAETTVRLR 1039 1800 DYPYRLWHYPCTVNYTIFKI 1040 1836 DYPYRLWHYPCTVNFTIFKI 1041 1801   AYSQQTRGLL 1042 1827 TAYSQQTRGLLG 1043 1829 SMSYTWTGALITP 1044 1838 SPGALVVGVI 1045 1843 LPRRGPRL 1046 Results of the secondary screening with individual peptides are summarized in Table 5. Altogether ˜20% of subjects (G05, G18, H02, H03, H04, H10, H12, H19, H32, H38) showed a significant IFN-gamma T-cell response against one ore more of the peptides. In some cases the observed number of ELIspots was clearly elevated, but not statistically significant above background. In these cases, PBMC (donors H03, H10, H33, H38) were stimulated with the respective peptides in vitro (2 rounds of in vitro priming, see Material & Methods) in order to increase the peptide specific response. Several peptides were confirmed in this way, results are again summarized in Table 5.

Peptides A3-A7 represent overlapping 15mers spanning the sequence TNPKPQRKTKRNTNRRPQD (SEQ ID NO:1047). Since they all react with PBMC from donor H03, the minimal sequence of the epitope is located within the sequence PQRKTKRNTNR (SEQ ID NO:1048). Prediction algorithms indicate that QRKTKRNTN (SEQ ID NO:1049) and QRKTKRNT (SEQ ID NO:1050) represent ligands of HLA-B*08, whereas RKTKRNTNR (SEQ ID NO:1051) most probably binds to HLA-B*2705.

Peptides C64-C70 represent overlapping 15mers spanning the sequence KGGRKPARLIVFPDLGVRVCE (SEQ ID NO:1052). C64 and C70 react with PBMC from donor H32 and H38, respectively. The minimal sequence of the epitope is therefore located within the sequence ARLIVFPDL (SEQ ID NO:1053). Prediction algorithms indicate that ARLIVFPDL (SEQ ID NO:1053) represents a ligand of HLA- HLA-B*2705 and HLA-B*2709. TABLE 5 Summary of HCV peptides reactive with PBMC. Numbers represent peptide-specific IFN-gamma secreting T- cells/10⁶ PBMC calculated from ELIspot results (duplicate determinations); values >8 (>3x over background) were regarded statistically significant. Donors H32 and H33 are spontaneously recovered patients. Donors reactive directly ex vivo in IFN-gamma ELIspot with . . . reactive after 2 rounds HCV-derived peptides of in vitro stimulation Peptide H32 H33 ID G05 G18 H02 H03 H04 H10 H12 H19 SPR H38 H03 H10 SPR H38 1557 20 75 1577 15 30 165  1579 45 35 75 1605 25 1615 30 325  1624 30 55 30 420  1628 40 45 25 20 100  1629 30 70 15 1798 25 115  1799 20 90 1800 35 95 1801 20 20 A3 80 A4 15 A5 110  A7 70 A78 25 A170 35 A212 60 A241 35 B08 55 B38 30 B76 35 C64 30 C70 20 C92 25 C94 25 C97 35 C98 70 C100 60 70 C101 50 C102 20 C106 45 C112 20 C118 35 C120 25 45 105  C134 20 C138 30 . . . reactive after 2 Donors reactive directly ex vivo in IFN-gamma ELIspot rounds of in vitro with HCV-derived peptides stimulation Peptide H32 H33 ID G05 G18 H02 H03 H04 H10 H12 H19 SPR H38 H03 H10 SPR 1557 20 75 1577 15 30 165  1579 45 35 75 1605 25 1615 30 325  1624 30 55 30 420  1628 40 45 25 20 1629 30 70 15 1798 25 115  1799 20 90 1800 35 95 1801 20 20 A3 80 A4 15 A5 110  A7 70 A78 25 A170 35 A212 60 A241 35 B08 55 B38 30 B76 35 C64 30 C70 20 C92 25 C94 25 C97 35 C98 70 C100 60 70 C101 50 C102 20 C106 45 C112 20 C118 35 C120 25 45 105 

Example V Binding of HCV Derived Peptides to HLA class II Molecules

In addition to the peptides listed in Table 1, several new peptides incorporating sequences from overlapping reactive peptides or avoiding critical residues like cystein were synthesized (Table 4). These were retested for their affinities to class II soluble HLA molecules, and results were compared to those obtained with the original (Table 6). TABLE 6 Binding of selected HCV-derived peptides and their 15- mer counterparts to soluble HLA class II molecules (“+++” strong affinity, “++” intermediate affinity, “+” weak affinity, “−” no affinity, “nd” not done; core binding motifs are underlined) Peptide ID HLA-DRB1* SEQ ID Binding to soluble NO: Peptide sequences 0101 0401 0404 0701 1101 1054 1798   IGLGKVLVDILAGYGAGVAGALVAFK − − + ++ +/− 1055 B84 GSIGLGKVLVDILAG + + + − 1056 B86   IGLGKVLVDILAGYG + ++ + + +/− 1057 B88     LGKVLVDILAGYGAG + ++ + 1058 B92         LVDILAGYGAGVAGA + − 1059 B94           DILAGYGAGVAGALV + − − − 1060 B96             LAGYGAGVAGALVAF ++ ++ − +/− +/− 1061 1799   AAWYELTPAETTVRLR +++ + + − +/− 1062 B46 AGAAWYELTPAETTV +++ +++ +++ − +/− 1063 B48   AAWYELTPAETTVRL +++ +++ +++ − +/− 1064 1827 TAYSQQTRGLLG ++ − +/− + + 1065 C114 TAYSQQTRGLLGCIV +++ +/− +/− + ++ 1066 1829     SMSYTWTGALITP + − − + +/− 1067 1604 VVCCSMSYTWTGALITPC + + ++ ++ + 1068 1650 VDYPYRLWHYPCTVNFTIFKVRMYVGGVEHRL 1069 A130  DYPYRLWHYPCTVNF + ++ +/− 1070 A131   YPYRLWHYPCTVNFT − 1071 A135       LWH YPCTVNFTI FKV − − ++ 1072 A141             TVNFTIFKVRMYVGG − − +/− ++ 1073 A145                 TIFKVRMYVGGVEHR +/− − 1074 1651 VDYPYRLWHYPCTVNYTIFKIRMYVGGVEHRL 1075 1800  DYPYRLWHYPCTVNYTIFKI − − +/− ++ − 1076 A147  DYPYRLWHYPCTVNY − − 1077 A152       LWHYPCTVNYTIFKI − − 1078 A158             TVNYTIFKIRMYVGG − − +/− 1079 A162                 TIFKIRMYVGGVEHR +/− − 1080 1817                    RMYVGGVEHRL − − +/− 1081 1426  HMWNFISGIQYLAGLSTLPGNPA + + ++ ++ + 1082 1425     NFISGIQYLAGLSTLPGNPA ++ ++ ++ nd nd 1083 1006   MWNFISGIQYLAGLSTLPGN ++ + ++ nd nd

Abolished affinities to DRB1*0101 and DRB1*0401 molecules in the case of peptide 1798 in comparison with its shorter counterparts (B84-B96) is probably due to the long sequence (26 amino acids) which can have a secondary structure that prevents binding. It is to be expected that in vivo, upon proteolytic cleavage, peptide 1798 will give rise to two shorter class II epitopes. Removed cystein (C) residues in peptides 1827 and 1829 (derivatives of peptides C114 and 1604, respectively) seem to be crucial for binding to DRB1*0401 molecules but do not essentially change affinities to other tested DR subtypes.

Example VI Identification and Characterization of HCV-Epitope hotspots

Here a T-cell epitope hotspot (thereafter referred to as “hotspot”) is defined as a short peptide sequence at least comprising more than one T-cell epitope. For example, two or more epitopes may be located shortly after each other (shortly being defined as less than 5-10 amino acids), or directly after each other, or partially or even fully over-lapping. Hotspots may contain only class I or class II epitopes, or a combination of both. Epitopes in hotspots may have different HLA restrictions.

Due to the highly complex and selective pathways of class I and class II antigen processing, referred to in the introduction, T-cell epitopes cannot be easily predicted within the sequence of a polypeptide. Though widely used, computer algorithms for T-cell epitope prediction have a high rate of both false-negatives and false-positives.

Thus, as even individual T-cell epitopes are not obvious within the sequence of a polypeptide, the same is even more the case for hotspots. Several radically different experimental approaches are combined according to the present invention for T-cell epitope identification, including epitope capture, HLA-transgenic animals and in vitro stimulation of human mononuclear cells. All three approaches are systematically applied on overlapping peptides spanning the antigen of interest, enabling comprehensive identification of epitopes (refer to CMV Epitope Capture patent). Upon such a comprehensive analysis, not limited to a particular HLA allele, but rather unravelling all possibly targeted epitopes within a population, epitope hotspots may become apparent. Within an antigen, only few if any sequences show characteristics of hotspots. Thus the identification of a hotspot is always a surprising event.

T-cell epitope hotspots offer important advantages: Hotspots can activate and can be recognized by different T-cell clones of a subject. Hotspots (when comprising epitopes with different HLA restriction) can interact with T-cells from different non HLA-matched individuals.

Epitope-based vaccines, so far have aimed at selected prevalent HLA-alleles, for instance HLA-A2, which is expressed in about half of Caucasians. Since other alleles are less frequent, epitope-based vaccines with broad worldwide population coverage will have to comprise many different epitopes. The number of chemical entities (for instance peptides) of a vaccine is limited by constraints originating from manufacturing, formulation and product stability.

Hotspots enable such epitope-based vaccines with broad worldwide population coverage, as they provide a potentially high number of epitopes by a limited number of peptides. TABLE 7 T-cell epitope hotspots in conserved regions of HCV. Hotspots (incl. some variations) are shown in bold, epitopes contained within the hotspots in normal font. Peptide number and sequence, as well as HLA-class I and class II coverage are given. Source data refers to Examples and Tables within this specification, or literature references. peptide ID peptide sequence Class I class II source data 1835 KFPGGGQIVGGVYLLPRRGPRLGVRATRK A2, A3, B7 DR11 Example III, VI (SEQ ID NO: 1084) 83 KFPGGGQIVGGVYLLPRRGPRL A2      B7 DR11 Example VI (SEQ ID NO: 1085) 1051             YLLPRRGPRL A2 Bategay 1995 (SEQ ID NO: 1086) 1843               LPRRGPRL B7 Example III (SEQ ID NO: 1087)                   GPRLGVRAT B7 Koziel 1993 (SEQ ID NO: 1088)                     RLGVRATRK A3 Chang 1999 (SEQ ID NO: 1089) 84 GYKVLVLNPSVAAT DR1,4,7,11 Tab.2: A200-A206 (SEQ ID NO: 1090) AYAAQGYKVL A24 prediction (SEQ ID NO: 1091) 84EX AYAAQGYKVLVLNPSVAAT A24 DR1,4,7,11 Example VI (SEQ ID NO: 1092) 87 DLMGYIPAV A2 Sarobe 1998 (SEQ ID NO: 1093)    GYIPLVGAPL A24 prediction (SEQ ID NO: 1094) 87EX DLMGYIPLVGAPL A2,A24 Example VI (SEQ ID NO: 1095) 89                 CINGVCWTV A2 Koziel 1995 (SEQ ID NO: 1096) 1577 GEVQVVSTATQSFLAT DR 4, 7 Tab.2 (SEQ ID NO: 1097) 89EX GEVQVVSTATQSFLATCINGVCWTV A2 DR 4, 7 Example VI (SEQ ID NO: 1098) 1426 HMWNFISGIQYLAGLSTLPGNPA A2 DR1,4,7,11 Example VII (SEQ ID NO: 1099) 1006  MWNFISGIQYLAGLSTLPGN Example VII (SEQ ID NO: 1100) 1425    NFISGIQYLAGLSTLPGNPA Example VII (SEQ ID NO: 1101)          QYLAGLSTL (SEQ ID NO: 1102) A24 prediction 1334 HMWNFISGI A2 Wentworth 1996 (SEQ ID NO: 1103) 1650 VDYPYRLWHYPCTVNFTIFKVRMYVGGVEHRL Cw7,A2,A24, DR1,4,7,11 Tab. 2,3,6 (SEQ ID NO: 1104) A11 ,A3 Example III 1836 DYPYRLWHYPCTVNFTIFKI Cw7,A2;A24, DR1,4,7,11 Tab. 2,3,6 (SEQ ID NO: 1105) A11 1846 DYPYRLWHYPCTVNFTIFKV Cw7,A2;A24, DR1,4,7,11 Tab. 2,3,6 (SEQ ID NO: 1106) A11 Example III 1651 VDYPYRLWHYPCTVNYTIFKIRMYVGGVEHRL Tab. 2,3,6 (SEQ ID NO: 1107) 1800  DYPYRLWHYPCTVNYTIFKI Cw7,A24,A11 DR7 Tab. 2,5,6 (SEQ ID NO: 1108) 1754  DYPYRLWHY Cw7 Lauer 2002 (SEQ ID NO: 1109) 1815          TVNYTIFKI A11 prediction (SEQ ID NO: 1110) 1816          TINYTIFK A11 Koziel 1995 (SEQ ID NO: 1111)          TVNFTIFKV A11 prediction (SEQ ID NO: 1112)         HYPCTVNYTI A24 prediction (SEQ ID NO: 1113)         HYPCTVNFTI A24 prediction (SEQ ID NO: 1114)                      RMYVGGVEHR A3 Chang 1999 (SEQ ID NO: 1115) 1799 AAWYELTPAETTVRLR B7? B35 DR1, 4 Tab. 2,5,6 (SEQ ID NO: 1116) 1818       TPAETTVRL B7? B35 Ibe 1998 (SEQ ID NO: 1117) 1827EX   GWRLLAPITAYSQQTRGLLGCIV A2,A3,A24, DR1,4,7,11 Example VI (SEQ ID NO: 1118) B8 C114           TAYSQQTRGLLGCIV A24, B8? DR1,4,7,11 Tab.2, 6 (SEQ ID NO: 1119) 1827           TAYSQQTRGLLG A24, B8 DR1, 7,11 Tab.6 (SEQ ID NO: 1120) C112 GQGWRLLAPITAYSQ A3?,A2?, DR1 Tab.2, 5 (SEQ ID NO: 1121)     RLLAPITAY A3 prediction (SEQ ID NO: 1122) C114EX GQQWRLLAPITAYSQQTRGLLGCIV A24,A3?,A2?, DR1,4,7,11 Tab. 2, 5, 6 (SEQ ID NO: 1123) B8? 1827EX GQGWRLLAPITAYSQQTRGLLG A24,A3?,A2?, DR1, 7,11 Tab. 2, 5, 6 (SEQ ID NO: 1124) B8? 1801        AYSQQTRGLL A24 Tab. 5 (SEQ ID NO: 1125) 1819        AYSQQTRGL A24 Kurokohchi 2001 (SEQ ID NO: 1126) 1798 IGLGKVLVDILAGYGAGVAGALVAFK A2,24,3,11 DR1,4,7 Tab.2,3,5,6 (SEQ ID NO: 1127) 1820          ILAGYGAGV A2 Bategay 1995 (SEQ ID NO: 1128) 1821                  VAGALVAFK A3,11 Chang 1999 (SEQ ID NO: 1129)             GYGAGVAGAL A24 prediction (SEQ ID NO: 1130) 1604 VVCCSMSYTWTGALITPC A2,A24,B7 DR1,4,7,11 Tab.2,3,6 (SEQ ID NO: 1131) 1829     SMSYTWTGALITP A2,A24,B7, DR1,7,11 Tab.6 (SEQ ID NO: 1132)     SMSYTWTGAL A2,B7 prediction (SEQ ID NO: 1133)       SYTWTGALI A24 prediction (SEQ ID NO: 1134) 1579 FTDNSSPPAVPQTFQV A1,2;B7,51 DR53 = B4*01 Tab.5 (SEQ ID NO: 1135) 1624 LEDRDRSELSPLLLSTTEW A1,2,3,26 DR7 Tab.2,3,5 (SEQ ID NO: 1136) B8,27,4402,60 1848 LEDRDRSELSPLLLST A1,2,3,26, DR7 Example VI (SEQ ID NO: 1137) B8,27,4402,60      RSELSPLLL A1 prediction (SEQ ID NO: 1138)        ELSPLLLST A2,A3 prediction (SEQ ID NO: 1139)   DRDRSELSPL A26,B27 prediction (SEQ ID NO: 1140) LEDRDRSEL B08,B4402 prediction (SEQ ID NO: 1141) 1824 LEDRDRSEL B60 Wong 2001 (SEQ ID NO:1142) 1547 YLVAYQATVCARAQAPPPSWD A2 DR1,4,7,11 Tab.2,3 (SEQ ID NO: 1143) 1822 YLVAYQATV A2 Wentworth 1996 (SEQ ID NO: 1144) A1A7 MSTNPKPQRKTKRNTNR A11,B08,B27 Tab.5 (SEQ ID NO: 1145) A3A7       PQRKTKRNTNR B08,527 Tab.5 (SEQ ID NO: 1146)        QRKTKRNTN B08 prediction (SEQ ID NO: 1147)         RKTKRNTNR B2705 prediction (SEQ ID NO: 1148) MSTNPKPQR A11 prediction (SEQ ID NO: 1149) MSTNPKPQK A11 Wong 1998 (SEQ ID NO: 1150) A122EX LINTNGSWHINRTALNCNDSL A2,2,3,B8 DR1,4,7,11 Tab.2,3 (SEQ ID NO: 1151) A122     NGSWHINRTALNCNDSL A2 DR1,4,7,11 Tab.2,3 (SEQ ID NO: 1152) LINTNGSWHI A2,3 prediction (SEQ ID NO: 1153)        RTALNCNDSL A2 prediction (SEQ ID NO: 1154) 1825 LINTNGSWHINRTALN A2,3,B8 prediction (SEQ ID NO: 1155) 1826       SWHINRTALN B8 prediction (SEQ ID NO: 1156) A241 TTILGIGTVLDQAET A2,A3 DR1, 4 Tab.2,5 (SEQ ID NO: 1157) TTILGIGTV A2 prediction (SEQ ID NO: 1158)   TILGIGTVL A3 prediction (SEQ ID NO: 1159) B8B38 FDSSVLCECYDAGAAWYE A1,2,3,26 Tab.5 (SEQ ID NO: 1160) B8 FDSSVLCECYDAGCA A3,A26 Tab.5 (SEQ ID NO: 1161)     VLCECYDAGA A2 prediction (SEQ ID NO: 1162) B38    VVLCECYDAGAAWYE A1 Tab.5 (SEQ ID NO: 1163) C70EX       ARLIVFPDLGVRVCEKMALY A2,A3,B27 Tab.5 (SEQ ID NO: 1164) C64-C70       ARLIVFPDL B*2705?,*2709? Tab.5 (SEQ ID NO: 1165) 1831        RLIVFPDLGV A2 Gruener 2000 (SEQ ID NO: 1166) 1832                  RVCEKMALY A3 Wong 1998 (SEQ ID NO: 11670) C92 AFCSAMYVGDLCGSV A2,B51 DR1,4 Tab.2,5 (SEQ ID NO: 1168) C97 GVLFGLAYFSMVGNW A2,3,26, DR1,4,7 Tab.5 (SEQ ID NO: 1169) B2705,51 C106 TRVPYFVRAQGLIRA A3,24, DR1,4,7 Tab.2,5 (SEQ ID NO: 1170) B7,B8,B2705 C134 TTLLFNILGGWVAAQ A2 DR1,7,11 Tab.2,5 (SEQ ID NO: 1171) 1823     LLFNILGGWV A2 Bategay 1995 (SEQ ID NO: 1172)

Example VII HCV Epitope Hotspot Ipep 1426 Contains at Least HLA-A*201 and Several Promiscuous Class II T-Cell Epitopes

The major objective of this experiment was to compare the immunogenicity of the “hospot” Ipep 1426, which contains at least one HLA-A*0201 epitope (Ipep 1334) and 2 promiscuous class II epitopes (Ipeps 1006 and 1425), to the individual epitopes. To this end peripheral blood mononuclear cells (PBMC) from several healthy HLA-typed blood donors were stimulated in vitro either with 1426 or a mixture of 1334, 1006, 1425. Three rounds of stimulation were performed resulting in oligoclonal T cell lines. Then, responses against all four peptides were assessed by interferon-gamma (IFN-γ) ELIspot analysis.

Peptide 426, induces T cell responses similarly well as individual epitopes comprised within its sequence. In particular CD8 positive T cells directed against the HLA-A*0201 restricted epitope 1334 were successfully generated. TABLE 8 peptide induced IFN-γ secretion of oligoclonal T cell lines. Lines were generated from two HLA-typed healthy individuals by 3 rounds of in vitro priming with either peptide 1426 or a mixture of peptides 1006 + 1425 + 1334. The reactivity of CD4 and CD8 positive T cells in these lines was assessed by IFN-γ ELIspot (“+++” very strong, “++” strong, “+” significant, “−” no IFN-gamma secretion). Donor HLA A*0206, A*01, A*0201, A*03, B7, B60; B27, B50; DRB1*1501, −B1*1302 DRB1*0401, −B1*1402 line line raised raised line raised line raised against against against 1006 + against 1006 + Peptide ID 1426 1425 + 1334 1426 1425 + 1334 1006 ++ ++ ++ ++ 1425 +++ +++ +++ ++ 1334 + + − − 1006 + 1425 + 1334 ++ ++ ++ ++ 1426 +++ +++ +++ ++ 84 (HCV − − − − derived negative control)

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1-28. (canceled)
 29. A method for isolating Hepatitis C Virus peptides (HPs) or isolating HCV T cell epitopes which have a binding capacity to a MHC/HLA molecule or a complex comprising the HCV-peptide or HCV T cell epitope and the MHC/HLA molecule, the method comprising: providing a pool of HCV-peptide, the pool containing HCV-peptides which bind to the MHC/HLA molecule and HCV-peptides which do not bind to the MHC/HLA molecule; contacting the MHC/HLA molecule with the pool of HCV-peptides whereby a HCV-peptide which has a binding capacity to the MHC/HLA molecule binds to the MHC/HLA molecule and a complex comprising the HCV-peptide and the MHC/HLA molecule is formed; and detecting the complex.
 30. The method of claim 29, further comprising separating the complex from the HCV-peptides which do not bind to the MHC/HLA molecule.
 31. The method of claim 29, further comprising isolating and characterizing the HCV-peptide from the complex.
 32. The method of claim 29, further defined as a method for isolating HPs.
 33. The method of claim 29, further defined as a method for isolating HCV T cell epitopes which have a binding capacity to a MHC/HLA molecule or a complex comprising the epitope and the MHC/HLA molecule, the method further comprising: assaying the HCV-peptide or the complex in a T cell assay for T cell activation capacity; and providing the HCV-peptide with a T cell activation capacity as HCV T cell epitope or as complex.
 34. The method of claim 33, further comprising isolating and characterizing the HCV-peptide from the complex before assaying the HCV-peptide.
 35. The method of claim 29, wherein the pool of HCV-peptides comprises a pool of peptides.
 36. The method of claim 35, wherein the pool of peptides is further defined as a pool of overlapping peptides, a pool of protein fragments, a pool of modified peptides, a pool obtained from antigen-presenting cells, a pool comprised of fragments of cells, a pool comprised of peptide libraries, a pool of (poly)-peptides generated from a recombinant DNA library, a pool of proteins and/or protein fragments from HCV, or a combination of any of these.
 37. The method of claim 36, wherein the pool is obtained from a total lysate or fraction of antigen-presenting cells.
 38. The method of claim 37, wherein the pool is obtained from a fraction eluted from surface or MHC/HLA molecules of the antigen-presenting cells.
 39. The method of claim 36, wherein the pool is comprised of fragments of HCV-containing cells, tumor cells, or tissue cells.
 40. The method of claim 39, wherein the pool is comprised of fragments from liver cells.
 41. The method of claim 36, wherein the pool is generated from a recombinant DNA library derived from pathogens or tumor cells.
 42. The method of claim 29, wherein the MHC/HLA molecules are HLA class I molecules, HLA class II molecules, non classical MHC/HLA molecules, MHC/HLA-like molecules or a mixture thereof.
 43. The method of claim 29, wherein the characterizing of the HCV-peptides of the complex comprises at least one of mass spectroscopy, polypeptide sequencing, a binding assay, identification of HCV-peptides by determination of their retention factors by chromatography, or a spectroscopic technique.
 44. The method of claim 43, wherein the characterizing of the HCV-peptides of the complex comprises a binding assay, further defined as an SDS-stability assay.
 45. The method of claim 43, wherein the characterizing of the HCV-peptides of the complex comprises identification of HCV-peptides by determination of their retention factors by HPLC.
 46. The method of claim 43, wherein the characterizing of the HCV-peptides of the complex comprises violet (UV) spectroscopy, infra-red (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD) spectroscopy, or electron spin resonance (ESR) spectroscopy.
 47. The method of claim 29, further comprising performing a cytokine secretion assay.
 48. The method of claim 47, wherein the cytokine secretion assay is an Elispot assay, intracellular cytokine staining, FACS, or an ELISA.
 49. The method of claim 29, wherein the T cell assay comprises the mixing and incubation of the complex with isolated T cells and subsequent measuring cytokine secretion or proliferation of the isolated T cells.
 50. The method of claim 29, wherein the T cell assay comprises measuring up-regulation of an activation marker.
 51. The method of claim 50, wherein the activation marker is CD69 or CD38.
 52. The method of claim 50, wherein the T cell assay comprises measuring down-regulation of a surface marker.
 53. The method of claim 52, wherein the surface marker is CD3, CD8 or TCR.
 54. The method of claim 29, wherein the T cell assay comprises measuring up-/down-regulation of mRNAs involved in T cell activation.
 55. The method of claim 54, further defined as comprising real-time RT-PCR.
 56. The method of claim 29, wherein the T cell assay is a T cell assay measuring phosphorylation/de-phosphorylation of components downstream of the T cell receptor, T cell assay measuring intracellular Ca⁺⁺ concentration or activation of Ca⁺⁺-dependent proteins, T cell assay measuring formation of immunological synapses, or T cell assay measuring release of effector molecules.
 57. The method of claim 56, wherein the T cell assay measures phosphorylation/de-phosphorylation of p56, lck, ITAMS of the TCR and the zeta chain, ZAP70, LAT, SLP-76, fyn, or lyn.
 58. The method of claim 56, wherein the T cell assay measures release of perforin, a granzyme, or granulolysin.
 59. The method of claim 29, further comprising formulating the peptide or epitope in a pharmaceutical composition.
 60. The method of claim 59, further comprising administering the pharmaceutical composition to the subject.
 61. The method of claim 60, wherein the subject is a human.
 62. The method of claim 60, further defined as a method of vaccinating the subject.
 63. The method of claim 61, wherein the subject is vaccinated against HCV. 